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CONTRIBUTIONS
COMPARATIVE  MYOLOGY
/
CHIMPANZEE.
r
By BURT G. WILDER.
COMMUNICATED TO THE BOSTON SOCIETY OF NATUKAL HISTORY,
         APEIL 17TH, 1861.
     CAMBRIDGE:
PRINTED BY H. O. HOUGHTO
         1861.
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CONTRIBUTIONS
                         TO THE

    COMPARATIVE  OTOLOGY  OF  THE  CHIMPANZEE.

                   By Burt G. Wilder.

   Through the kindness of Prof. Jeffries Wyman, I was en-
 abled last winter to dissect one side of a young male Chim-
 panzee,  Troglodytes niger, about two feet in height; as it
 had been kept in alcohol for two or three years, it could be
 examined more at leisure than a fresh specimen.  The dis-
 section was very carefully made, and with special reference
 to  the differences in the muscular  system  from that of
 man.  Believing the mere facts in Anatomy or  any sci-
 ence to  be in themselves worthless  till  so  grouped and
 studied  as to exhibit the uses or functions which they
 represent,  I  have  constantly  endeavored to  detect the
 meaning of the differences in  size, number,  and arrange-
 ment between the muscles of the  Chimpanzee and  those
 of man,  and  with this view have dissected portions of six
 other Quadrumana of the genera Macacus, Cynocephalus,
 and Ateles, and several lower animals, using also for com-
 parison the published or MS. notes of a  large number of
 other dissections.   (See list at the end of this paper.)  I
will speak first of  some muscles whose  functions are
chiefly local, and then more in detail  of the muscular sys-
tem as  adapted to  the climbing  habits of the  Quadru-
mana.
                 1
 
354                Contributions to the
  Occipito-frontalis.   The apes have been generally sup-
posed to possess the power of moving the eyebrows  and
scalp, which man does by means of this muscle ;  in  him
the two muscular bellies are  short, the greater  part  of
the skull being covered by the thin aponeurosis which con-
nects them.  I have dried and  preserved the right half  of
this muscle from the Chimpanzee which I dissected; the
fleshy fibres are proportionally much longer than in man,
and seem to meet upon the vertex;  the occipital portion
is quite fleshy and distinct, but the frontal portion is thin-
ner and more closely united with the thick skin, so that,
commencing in  that region,  one might very easily over-
look it, as  I did at first.  Tyson and Traill say they could
not find it in their specimens, and no other authors men-
tion it,  except Prof. Owen,  who found it in an  Orang
{Simla Satyrus), and partly in a Chimpanzee. (4.)   There
were evidences of it  in a Cynocephalus and in the Macaci
which I dissected, hut I did not trace it in its whole extent.
   The  muscles of the ear have been as little  noticed  by
anatomists;  the ear of  this specimen had been  cut  off
before I dissected that region, so that I am not positive as
to the insertions into it;  but in the places of the Attraliens
and Retrahens aurem were series of muscular fibres  con-
verging towards the  ear,  their upper borders touching the
lower border of the  Occipito-frontalis; they seemed to  be
more extensive  than in  man.   On  the  upper  surface of
part  of the parietal and frontal portions of the  Occipito-
frontalis may be seen a thin layer of muscular fibres, about
two inches in width, near the sagittal suture, thence con-
verging downward towards the ear.   If this represents the
Attollens aurem, it is much more extensive than in  man.
   Cutaneous muscles.   In the Chimpanzee, as in the Go-
rilla and Orang, the Platysma myoides is rather thicker than
in  man, but I could find no cutaneous muscles upon the
trunk as in the lower animals.   There was  a distinct Der- 
         Comparative Myology of the Chimpanzee.     355

 mo-humeralis  in  each of the  two Cynocephali and three
 Macaci which I dissected, and it is not mentioned as ab-
 sent in the others.   It is generally inserted over the ten-
 don of the Latissimus dorsi, and would  thus  serve either
 to  wrinkle the skin, or to assist the latter muscle to flex
 the humerus,  as in climbing.
   Digastricus.  The anterior belly is much broader than
 in  man, being composed of two portions, — one  external,
 next the jaw bone, rounded and more  directly connected
 with the tendon, — the other internal  and twice as broad,
 reaching to the middle  line to  join that of the  opposite
 side.  The two muscles  fill the space between the rami of
 the jaw.
   Sterno-mastoid.   "Wholly distinct from  Cleido-mastoid.
 Occipital portion very broad,  the aponeurotic attachment
 reaching from just behind the  ear to the middle line on the
 superior occipital crest.   Thence downward it  gradually
 becomes narrower, thicker, and more rounded,  crossing the
 Cleido-mastoid to be inserted by a short, round tendon
 into the manubrium, as in man.
   Cleido-mastoid.  This is smaller than the preceding, and
 the reverse in shape, the small  end being above, and at-
 tached to the skull  just within the anterior  edge of the
 Sterno-mastoid, while the lower end is wider and inserted
 into the upper border of the clavicle, near the sternum.
 In the Gorilla, according to Duvernoy, the sternal portion
 of the Sterno-cleido-mastoid is very small, the whole ap-
 pearing as one muscle, which is almost wholly attached to
 the clavicle, and there are not two  separable  portions ;
 but in Prof. Wyman's specimen it  resembled  that of this
 Chimpanzee.
  Trapezius.  I noticed  no  difference  in this from the hu-
 man, except that its  lower border, instead  of  overlapping
 the upper border of Latissimus dorsi, seemed to be  con-
tinuous with  it, as  mentioned by Vrolik,  who says  that 
356
Contributions to the
this  connection  does not exist in other apes.   Tyson's
plate is not very distinct, but he does not say that it differs
from the human.  In the Gorilla, according to Duvernoy,
it is as in man.
  Rhomboidei.  In the Quadrumana generally, these form
but one muscle.   In  the Orang, and in the Inui and Cy-
nocephali, (8.) the single muscle is attached to the occiput,
thus serving to support the head.
  Levator-anguli-scapulae.   Did not  differ  from the hu-
man ; in a Cynocephalus and  Macacus it was continuous
below with the Serratus magnus, of which  it would thus
seem to be  merely  a continuation.  In  the  Macacus it
arose from the transverse processes  of all the cervical verte-
brae, and perhaps from the occiput and first dorsal vertebra.
  Levator clavicular (Tyson),  Trachelo-clavicular, or Tra-
chelo-acromialis.   This  muscle is  not found in man, but
appears to exist under some  form in most of the lower ani-
mals.  In tHis specimen it was quite strong, but I did not
see its origin, which is generally from the transverse pro-
cesses of some of the upper cervical vertebrae.
  Serratus magnus.   Composed of two fleshy parts, with
an intervening thin portion.   The  superior part seemed to
arise from the first and third ribs, thence becoming wider,
to be inserted into about an inch  of the upper angle and
posterior border of the  scapula.   The  inferior portion is
much larger, arising from the eight ribs  below the third,
thence narrowing to  its insertion into the  lower angle and
part of the  posterior border of the scapula, without any
tendon.  I did not see that the intervening thin portion
was anything more than a thin membrane.
  Subclavius.  I am quite  sure that it was  present, but
did not note its connections.   Mr.  Moore  thinks he saw it
on the right side  of this specimen.  It is generally pres-
ent in Quadrumana, and larger than in man, in accord-
ance with the greater mobility of the shoulder. 
         Comparative Myology of the Chimpanzee.     357

   Costo-coracoid ligament.  Connects the cartilage of first
 rib near the sternum with the coracoid process.  Duvernoy
 thinks that this takes the place of the  Subclavius  in  Go-
 rilla ; but they both existed in this Chimpanzee.
   Coraco-brachialis.  Does not seem to reach the coracoid
 process at all, except through the tendon of the short head
 of the Biceps, to which, and to the upper part of the  muscle
 itself, its fleshy fibres are attached; its insertion, I think,
 was not more than one half an inch long, one third down
 the humerus.  In Prof. Wyman's Gorilla this attachment
 was from the surgical neck as low down as the middle of
 the humerus.
   Before describing the muscles employed in climbing, let
 us first consider how  far this principal mode of locomotion
 of the Quadrumana differs from that of man.
   The Quadrumana  are all  more or less perfectly adapted
 for climbing;  but as  those of the  old  world form  two
 groups, — the  Anthropoids,  including the  Chimpanzees,
 Orangs, and Gibbons, with  very long and powerful arms
 and short  legs, fitting them well for climbing, but poorly
 for walking;  and the Baboons and Monkeys, (Cynocephali,
 Macaci, &c.) whose limbs are of nearly equal length  and
 power, and who climb or walk on all fours with about the
 same facility, — so in the new world are  two correspond-
 ing groups, the Howling-Monkeys, the Ateles, &c,  with a
 long  and generally powerfully prehensile tail,  all  being
 very agile  climbers;  and the  Cebidae, Sakis, and others
 whose tail is not prehensile, and who go often upon all-
 fours.   So much do  the  Anthropoids resemble ourselves
 in external form and  in their attitudes, as we  see them in
 captivity or represented in  books, and  so nearly also does
their internal structure  correspond with our own, that we
are very apt to overlook the radical  distinction in their
mode of locomotion, and to believe that in this as in other
 respects they form the physical transition between the lower 
358
Contributions to the
animals and man.  We walk upright upon the earth, and our
whole frame is perfectly balanced in that position ; we are
supported from below by comparatively narrow pedestals ;
our whole weight is in direct opposition  to the erect posi-
tion, and, as soon  as we declined from it, would force us
to the  earth but for the preponderance  in the back and
legs, of the extensor over the flexor muscles.   The position
of the ape  in nature is just the reverse :  he hangs and
moves about among the trees by means of  his long arms,
being thus  sustained, not from below, but from  above ;
and his  weight would soon bring him to  the earth but for
the immense power of the flexor muscles in the arms.  In
our arms, and  in the legs of the ape, the two systems of
muscles are more  nearly equal.   Our legs are solely for
locomotion, our  arms solely for prehension, and both  pre-
sent  the perfection of  structure  which  would  naturally
attend so high a degree  of specialization  of function ; but
both the upper and lower limbs of the ape may be employed
as organs of either support or prehension, and we therefore
remark  in  them a corresponding want of complete adap-
tation to either of these functions ; yet these so diverse mo-
tions of man and apes are performed by almost identical
muscles, while in the bird, which, like man, walks upon two
legs, with a very characteristic motion of the anterior ex-
tremities, the muscles are with great difficulty homolo<nzed
with the human. We see also that in both man and ape the
greatest weight of the body is placed  nearest the organs of
support, which is a further proof of the inability of the for-
mer to climb, and of the latter to walk, with ease; and the
depressed head of the ape, and the proportions of the neck,
which is shorter than in  man compared with the length of
the arms, also  offer the least hindrance to the free suspen-
sion and movement of the trunk by the arms.   The great
length of the ape's arm, especially below the elbow, how-
ever  useful in  climbing, deprives him in a measure of the 
         Comparative Myology of the Chimpanzee.     359

facility we possess of touching with the fingers every por-
tion of the body; and we should hardly wish our arms so
long as  to render the most convenient way of scratching
the middle of the  back, passing the hand  between  the
leg:*, and up  behind to the point desired, as has been said
of one species.
   So far as  the arms  are concerned, the climbing of the
ape consists  in their alternate extension towards and con-
traction  from some  point above, thus elevating the body
to it.  The shoulder is much more movable than in man,
and has an additional elevator, Levator claviculce.  It is de-
pressed by the lower part of the Trapezius, by the Serratus
magnus, Subclavius, and Pectoralis minor;  this latter is
quite variable in its insertion, which is sometimes into the
coracoid process as in man, and sometimes into the great
tuberosity of the humerus ; in this Chimpanzee the former
was the  case on the left side, but the latter on the right
side.   In the Gorillas of Prots. Wyman and Duvernoy
the muscle was composed of two  portions, of which  the
upper was inserted into the coracoid process, and the lower
into the tendon of  the short head  of  the  Biceps, so that
when the arm was raised, it might act  as a flexor of both
humerus and fore-arm.   In the  lower  species, the muscle
is generally longer than in man, and  more or less sub-
divided,  and its insertion is usually into the  humerus.
The arm is raised from the side by the Deltoid, which is
extremely thick and powerful, as is required by the  length
and weight of the limb; there is also an additional infra-
spinous  portion of  this muscle  arising from  the fascia of
the Infraspinatus and from the lower third of the anterior
border of the scapula, which would better enable the Chim-
panzee to swing the arm  backward.  The Deltoid, Supra
and lnfraspinati,  Teres minor, and Subscapularis  are a
great protection to the joint.
  The humerus is depressed, or, the hand  being fixed, the 
360
Contributions to the
body is raised by the Pectoralis major in front, the Latis-
simus dorsi behind, and the  Teres major arising from  the
lower  half of the anterior border of the scapula  between
them.   The three are very thick and strong; the sternal
portions of the  Pectorales majores  nearly touch on  the
middle line, but there is no division between them and  the
clavicular portions,  though the fibres cross before their in-
sertion as  in man.   The  tendons of these three muscles
pass round the inside of the humerus towards the upper
surface, so as by their contraction to throw the elbow out-
wards, and keep the thumb and radial side of the forearm
inward and upward, which is obviously the  most advan-
tageous position.  In the lower species the Dermo-humer-
alis, described above, acts as a second Latissimus dorsi,
though of course  much  more feebly.  The scapular  head
of the Triceps, though  part  of the extensor, is  neverthe-
less, when acting alone or with the other flexors of  the
humerus, a powerful aid in  climbing, its  extensor power
being  counteracted  by the flexors of the  forearm, which
act at  a greater mechanical advantage, so that it can then
act only as a flexor  of the humerus.
  In man there is occasionally found as an anomaly, a mus-
cular slip on the inside of the arm, from the tendon of the
Latissimus dorsi to some part of the elbow ; in most of  the
Quadrumana, and in very many other animals, this  mus-
cle  is  constantly  present, though varying as to  size and
insertion in different species ; it does  not seem  to  have
been described with much accuracy ; in the lower animals
it is often so large as to be called the fourth head of  the
Triceps; in the  Quadrumana it is  generally named the
" slip from Latissimus dorsi to elbow," with  a conjecture
that it may  be  of  some  use in  climbing;  this  it never
could be, but the reverse, acting as part of the extensor ;
but even if inserted into the olecranon or upon the Tri-
ceps, as it  sometimes is, it would  be of the  same use in 
         Comparative Myology of the Chimpanzee.     361

 climbing as the scapular head of that muscle ;  but in  a
 large number of cases it is attached to or over the internal
 condyle of the humerus, thus acting only to draw the  arm
 and body together, without at all interfering  with  the
 simultaneous flexion of the forearm  at the elbow.  Duver-
 noy describes it in the Gorilla under the name of " Dorso-
 epitrochlien"  and he  seems  to  have understood its  true
 function better than any one else.   In the lower Quadru-
 mana, while on all fours, as  in  Quadrupeds, this  muscle
 simply helps to retract the fore-leg ; in the cat which climbs,
 and in  the  same way as we do, by  contracting the whole
 limb, it is inserted  into the internal condyle; but in the
 Angora Goat, whose  so-called climbing  is merely a tall
 kind of walking, it is  almost wholly attached to the long
 olecranon, tending thus to extend or straighten the whole
 limb at the  same time that it pulls it backward.
   The  muscles which flex the  arm at the elbow are the
 same as in man, — Biceps,  Brachialis anticus, and Supi-
 nator longus.   The two heads of the first are distinct to
 within  an inch of the  insertion, and the coracoid head is
 the larger.  The  Brachialis anticus is not easily separable
 into two parts, or as easily into several.  In the Supinator
 longus  we notice  at once  a feature which exists also in
 the flexors of the  leg;  its origin is  from  the  two inches
 below the middle of the  humerus, thus as high  as  the
 Brachialis anticus, and  much higher than  in man ; while
 this  disposition of the flexors mars the symmetry of both
 elbow and knee;  combined with the constant partial flex-
 ion  of  the arm and leg it confers upon  the ape greater
 readiness and power of contraction.  The length of the
 belly of the Supinator longus  is to that of the tendon as
 five and a half to one and a fourth.
  From the direction of the force, the Supinator  longus is
 a very feeble  supinator, much more so  than the Biceps,
which also can turn the palm fairly upward, while the  for-
                  s 
362
Contributions to the
mer can only bring the thumb or radial side of the hand
uppermost;  then continuing to act, it is a simple flexor of
the forearm, with of course more  power the higher it is
attached upon the humerus; in fact the  Supinator longus
bears the same relation to the humerus when the hand is
fixed, as in climbing, that the Biceps bears to the forearm
when the shoulder is the  fixed point.  Both muscles may
act as either flexors or supinators ; in the former case their
effect as supinators must  be counteracted by the Pronator
teres, which  then is also a flexor, and in the latter case the
Triceps may be felt to contract to prevent flexion, and also
to fix the ulna.  The gradual disappearance in  the Quad-
rumana of the power  of  rotating the forearm, which is so
complete in man, is well  described  by Vrolik (7, page 30).
The  most natural, and therefore  the most useful position
of the  forearm  in the climbing  Quadrumana, is midway
between  pronation and supination, when  the   Supinator
acts  freely as a flexor.  While dissecting an Angora goat
last winter, I was much interested to observe that the Biceps
had two distinct tendons of insertion, of which  one, repre-
senting the single tendon  of man and in the  Quadrumana,
ran round the neck of the pronated radius, to be attached
to its lower surface, while the other extra tendon was  in-
serted  at  once  into the  upper border of the bone; this
double tendon, adapted to the flexion of the  forearm in its
state of permanent pronation, is a good example of the
adherence to a general plan, with the addition of a part
for special use, or, from the opposite point of view, of the
total disappearance of a  part when no longer  needed.  I
found the  same structure  in a young sheep, but  have never
noticed it in the Carnivora.  The flexors and extensors of
the wrist do not differ from those in man, except that the
Flexor ulnaris is larger, as also the pisiform bone to which
it  is  attached.  In the Chimpanzee, as in man,  the Flexor
carpi ulnaris is more powerful than  the Flexor  carpi radi- 
         Comparative Myology of the Chimpanzee.     363

alls;  the former  is clearly the one which we use in the
more forcible movements of the hand at the wrist, in strik-
ing a blow, or  in reaping with a sickle; it is also full as
good  a supinator as the Supinator longus, and in nearly
all actions requiring forcible supination, as turning a han-
dle, &c, the hand is flexed to the ulnar side at the same
time.
   It is a general  rule, that two contiguous segments of a
limb  are flexed in opposite directions, as is well shown in
the human  lower extremity, where  thigh, leg, foot,  and
toes all bend thus contrary to each other, the flexor mus-
cles of one  segment lying, of course, on the same side of
the limb with  the extensors of the segment next below.
This  holds  good in the leg and upper arm of most  ani-
mals  as well as  man, but in nearly all, the hand and fin-
gers,  and, if the hand is supinated as in man and Quadru-
mana, the forearm also, appear to be flexed or extended in
the same direction, so  that two, or even three groups of
muscles, which by their contraction shorten the  arm, lie
all upon the same  side of the limb,  though  attached to
three contiguous  segments,—forearm, hand, and fingers.
But to carry out the idea of " antero-posterior symme-
try "  or  antagonism between the corresponding segments
of the fore  and  hind limbs, the supinated hand must be
placed palm downward, with the fingers pointing back-
ward, when of  course the muscles now called extensors of
the wrist or hand will become the flexors, and vice versa,
and the contiguous segments will be flexed in opposite di-
rections.  During the earlier foetal periods the hand is  in a
state  of supination, and afterwards  becomes pronated, re-
maining so through life in the common Quadrupeds, only
some, as the higher Carnivora, the Quadrumana, and espe-
cially man,  having the power  of freely rotating it back
to its  original condition, which, of course, is more likely to
illustrate  the true morphology than  any afterwards ac- 
364                Contributions to the
quired.   Therefore, the muscles on the front  of the fore-
arm  attached  to the wrist are morphologically extensors,
although they will probably retain  the  functional name
of flexors, since by their contraction they  shorten the limb.
In the leg of man, the above rule obtains even as to the
slight lateral deflection at the joints, for the hip stands
outward, the knee inward, and the ankle again outward,
so that the  sole of the foot may be  inverted more easily
than everted, as is more strikingly shown by the  perma-
nent condition of the foot  in the ape, in whom, however,
the rule is infringed by the peculiar outward curvature  of
the whole limb for greater facility in climbing.  So when
the arm  is  placed in  the  position indicated above, the
shoulder stands outward, the elbow inward, and the wrist
again outward, the hand bending more naturally to the
ulnar than to the radial side ; and accordingly we find the
Flexor carpi ulnaris more powerful than the Flexor carpi
radialis,  and the hand of the Bird is permanently flexed  to
the ulnar side.  The use of the  " antero-posterior symme-
try" between scapula and ilium, humerus and femur, fore-
arm  and leg, in  the  common Quadrupeds, for better  bal-
ancing the  body when at  rest,  is evident;  but since the
animal when moving goes forward, the hand  is pronated
so that  the two  lower segments, which  are often much
elongated, both bend backward, affording a more extensive
motion  in that direction for propelling the  body forward.
But  in the  hind leg the segments below the knee,  and in-
deed below the hip, possess little separate motion, the
entire limb swinging nearly as a whole.
   The tendons of the deep common flexor of the  fingers,
[Flexor profundus digitorum) were so  short as not to per-
mit the simultaneous extension of both hand and  fingers;
the latter could be straightened only when the former was
at right  angles with the forearm, and when I bent the
hand back into  a straight line  the fingers  closed tightly 
Comparative Myology of the Chimpanzee.     365
upon mine.   The advantage of this to a climbing  animal
is at once apparent; the hand having been placed upon  a
branch, the mere weight of the body would cause the fin-
gers to close upon it like hooks without muscular exertion,
and they would retain their grasp till the strain was relieved
by means of the other limb.  How else can we explain the
power which some Orangs have  been said to possess, of
swinging upon a  rope by the  hands alone, for an hour at
a time?   It also readily accounts for the Anthropoids not
being able to apply their palms to the ground when on all
fours, but being obliged to rest on the knuckles.   I have
never seen any direct reference to this structure, but it has
always  been remarked that the digits of  both hands and
feet of the Anthropoids are generally flexed, giving them a
hook-like appearance.   By a similar structure, though not
nearly so marked,  the human hand may be bent backward
a little farther when the fingers are flexed than when they
are straight; and, the reverse of what exists in the Chim-
panzee, owing to the shortness of  the extensor tendons,
man's hand and fingers cannot be flexed far together, but
by bending forward the closed fist the fingers are gradually
forced open.
  In  general, the  muscles lying upon the forearm differ
from  our own in being less distinct from each other, and in
remaining fleshy often to the  wrist, allowing more  exten-
sive movements, but detracting much from the elegance
and pliability of the limb.
  Extensor communis  digitorum.  May be separated into
three  fleshy parts to  above the middle of the arm, and the
part supplying the index finger still  higher; this becomes
tendon  at the  wrist, the middle portion  about  an inch
higher, while that going to the ring finger is the  largest,
and continues fleshy below the end of the ulna ; the  ten-
don of the middle one is the largest.  The Extensor mini-
mi digiti is separate from the preceding as high as the part 
366                Contributions to the

supplying the index finger; it is slender, but  continues
fleshy below the wrist.  Neither Mr.  Moore  nor I found
any tendon from the Extensor communis to the little finger,
nor does Vrolik mention it; but there was such a tendon
very distinct in Duvernoy's  Gorilla.   The Extensor pro-
prius indicis was  as in man, but perhaps arose a little
lower down on  the ulna.
   Palmaris longus and P. brevis.  These are not constantly
present in the Quadrumana; the former was in this Chim-
panzee, as in  Vrolik's, but it does not exist in the Gorilla
according to Duvernoy, and Prof. Wyman does not men-
tion it.   It was wanting in one arm of Traill's  Chimpan-
zee, but present in the other, and Mr. Moore found it in the
right arm of Ateles Paniscus, while Mr. Folsom  did not in
the  left.  I did not see any P. brevis, but Vrolik says it
existed in his  specimen.   It was present in the  Gorilla of
Duvernoy, but not in that of Prof. Wyman.
   Flexor sublimis digitorum.   This in the left arm was as
in man, but in the right arm Mr. Moore is certain that the
ring finger received two tendons, and the little finger none.
 The Flexor profundus digitorum is very thick and strong.
 As in Duvernoy's  Gorilla, the portion supplying the index
finger is separate  from the rest, and joined with the long
 flexor of the thumb ; the remainder occupies the place of
the entire  Flexor communis in man.  (For the  shortness
 of its tendons, see above.)   The Flexor proprius indicis et
pollicis arises from the radius, in the position of the Flexor
pollicis only in man ; it sends a strong tendon to the index
 finger;  from the lower surface comes off a slender tendon
 which  is inserted  into the base of the second phalanx of
 the thumb.   The thumb has thus become merely an aid in
 the grasping of the fingers, with little or no  independent
 action.   A like arrangement  existed in Duvernoy's Go-
 rilla, but in Prof. Wyman's Gorilla, and in his and Traill's
 Chimpanzees, this muscle did not exist separate from the 
        Comparative Myology of the Chimpanzee.     367

rest.  Tyson says that the  muscles of the thumb  differed
not from  the human,  but there was no tendon  to  the
thumb in  Vrolik's specimen.   In the lower Quadrumana,
when there is any tendon for the thumb it generally comes
from the common flexor; there was none in  Ateles Panis-
cus, whose thumb is rudimentary;  in the Howling-Mon-
key there were four tendons, — one to the thumb,  but
none  to the  little finger.
   The  short muscles of the  thumb were all present,  but
thinner and  less  distinct than in man ;  they exist in  the
Gorilla and  Howling-Monkey, but  not in Ateles Paniscus,
except  perhaps a very little rudiment.  The Extensor lon-
gus pollicis  (secundi internodii) is present generally in the
Quadrumana.  The Extensor brevis pollicis (primi inter-
nodii) was quite as large as the  preceding, not smaller as
in man, and was inserted into the radial side of the base of
the metacarpal of the thumb, as in the specimens of Wyman
and Vrolik ;  Tyson says the insertion was as in man.   In
the Gorilla, Prof. Wyman does not mention any peculiarity;
and Duvernoy  says it  is as in man, but that it is want-
ing in  the  Chimpanzee, the  Abductor longus taking  its
place; in  this  Chimpanzee it was confounded with  the
latter only above.  It was  wanting in the Howling-Mon-
key, and in Prof. Wyman's Cynocephalus was joined to
the Abductor, which goes to the trapezium.   The Abductor
longus pollicis [Extensor ossis metacarpi) was inserted into
the trapezium,  as in the specimens of Prof. Wyman and
Vrolik,  and in Prof. W.'s Cynocephalus, but in the Howl-
ing-Monkey it  is as in man.  In  the left arm of Ateles
Paniscus  Mr. Folsom says it was present, but Mr. Moore
thinks that in the right arm it was  united with the Exten-
sor brevis, with a double tendon attached to both trape-
zium and  metacarpal bone.  See Duvernoy for his views
as to the homologies of these  three muscles.
  All the muscles of the little finger were present,  as also 
368
Contributions to the
 in  the Gorilla.  The Lumbricales were like the human,
 except that the slip supplying the little finger did not arise
 from the tendon of the deep flexor of that finger, but only
 from that of the ring finger.  The palmar Interossei were
 much, and the dorsal Interossei little, developed.
   I dissected the muscles of the back and of the abdomen
 only enough  to see that  the former,  as extensors, were
 weaker  than  in man, while the latter were stronger, both
 as very important flexors of the trunk, and as supports to
 the  viscera, in the creature's semi-erect position.
   Psoas parvus.  Absent on both sides of this individual.
 Not mentioned except by Tyson, who says it was  larger
 than in man.   Present  in  the  Gorillas  of Wyman and
 Duvernoy, in the Howling-Monkey, in  Macaci, and Cyno-
 cephali.
   Quadratus lumborum.   Shorter than in man,  as the
 Psoce and Illiacus are longer.  Mentioned only by Duver-
 noy as in the Gorilla, and by Wyman  as in the Howling-
 Monkey, where it is more slender than  in man, and  arises
 from the transverse  processes of the four  upper lumbar
 vertebras, and from  the body of the  first.
   Quadratus femoris.  Longer and narrower than in man,
 as noticed by Owen in the Orang, and naturally from the
 downward projection of the ischium.
  I am quite sure that the other rotators were  present, but
 at the time of the dissection I was not sufficiently familiar
 with their limits in  man to compare them with much cer-
 tainty.
  Pectineus and three Adductors.  These are present, but
 more intimately connected  than in man.  They form a
very large fleshy mass, and  are  inserted down the whole
length of the femur, the principal portion  of the Adductor
magnus being attached by a strong tendon to the internal
condyle.   They would not only adduct  the thigh strongly,
as in climbing, keeping the inverted sole against the tree, 
         Comparative Myology of the Chimpanzee.     369

but from the backward projection of the ischium, the Ad-
ductor magnus especially becomes a powerful extensor of
the limb for leaping.
   Psoas magnus.  Arises from the four lumbar vertebrae,
and perhaps from the thirteenth dorsal ; some fibres  also
seem to  come from the upper part of the ilio-pectineal line,
which may represent the small, distinct muscle of the
Orang,  described by Prof.   Owen as  coming  from the
fore part of the ilium, and inserted at the root of the tro-
chanter minor.  The Psoas  is blended with the  Iliacus in
the whole  length of the latter, and both continue fleshy
quite to  the insertion.
   Iliacus.   See Psoas magnus.
   Scansorius,  (Traill).    This  muscle  arises from  the
whole outer border of the ilium, nearly as far down as the
acetabulum, and is inserted into the lower part of the great
^trochanter, between the origins of the Vastus  externus and
Cruraeus.  It would rotate the thigh a  little  inward from
its usual position, but its use is most  obvious as an extra
flexor of the thigh ; it  is  a rather thin, but fleshy and per-
fectly distinct, broad, triangular muscle, but so far as I can
learn, it  has been found  only by Traill, who first  discov-
ered  it in  his Chimpanzee, and by  Prof.  Owen in his
Orang.  When its use is so  apparent, it is strange that it
should be so rare, and so variable in the same species.
   Rectus femoris anticus.  See Quadriceps femoris.
   Tensor vaginae femoris.  This was larger than in man,
and continuous with the upper  thin portion of the Glu-
tceus  maximus.   Like the Rectus, it would help  to  flex
the thigh.
   Glutaeus maximus.  Arises from the border of the lower
half of the sacrum and coccyx, from  the fascia  covering
the G. medius, from  the  great sacro-sciatic ligament, and
from the tuberosity of the ischium in close connection with
the long  head of the Biceps.   The upper part of  the mus-
                  3 
370               Contributions to the

cle is very thin, and  chiefly joins the Tensor vagina fem-
oris;  but the lower portion,  especially that from the isch-
ium, is very thick and strong, and inserted upon the whole
length of the femur from the base of the great trochanter to
the outer condyle, at which point it thickens and widens
some of its fibres  seeming to mingle  with those  of the
 Vastus externus.   This ischial portion in the Gorilla is de-
scribed by Duvernoy under the name of " Ischio-femorien."
Acting  alone, it would rotate the thigh outward, so as
to allow the sole of the  foot to be  turned  inward, after
which it would  assist the Adductors in  keeping the foot
close against the object  grasped in climbing, but  acting
with the  Glutceus medius,  it would help to  extend the
 thigh.
   Glutaeus medius.   As  in the Quadrumana generally,
 this  is  the largest  of the  three  Glutcei, being long and
 thick from the length and posterior concavity of the ilium.a
 It is attached to the tip of the great trochanter.
   Glutaeus minimus.   A thin, flat, radiated muscle cov-
 ering the posterior border of the acetabulum, and, I think,
 was  attached to the  great trochanter; I  am not  sure
 whether it arose at all from the coccyx.
   I think there  has  always  been some misapprehension as
 to the true functions and importance of the two great Glu-
 tcei as contrasted in man and the Quadrumana.   In  the
 latter they  are generally described as small and wreak ;
 whence the inability  of  these animals to  stand erect or
 upon one  leg as we do.  But, apart from the  grave error
 of stating an effect for a cause, the real distinction seems
 to me  to be not so  much in the size as  in the position
 of these muscles.  Man stands or walks erect with ease,
 and  his Glutcei are very  large ; the ape with difficulty ap-
 proximates to the erect position, and it is doubtful  if he is
 at all able  to stand  on  one leg,  whence it seems to be
 inferred that his  Glutcei must  be very small and weak. 
         Comparative Myology of the Chimpanzee.    371

 But suppose we had first studied their actions in the ape ;
 having seen that by  means  of  them he leaps well, and
 knowing that man does not leap  so well, the same reason-
 ing would lead us to believe that the Glutcei of man can-
 not be very large.   The truth is, that these same muscles
 perform two sets of movements in both man and the ape,
 but in the former they are so disposed, in conformity to
 the rest of his structure, as to be best adapted to assuming
 and maintaining the erect position, while in the latter their
 form and direction are so modified as to be more favorable
 to leaping.  Many of the lower animals, the Horse for in-
 stance,  have a very  large  Gluteus medius.   Yet they
 never stand erect.  It is the muscle  with which they kick,
 and kicking differs  from leaping only in the position of
 the fixed point  of the action.  I do not believe that the
 size alone  of the Glutcei in the ape has any influence upon
 his natural attitude, but that if his body and legs were so
 balanced as to enable him to assume the erect position at
 all, the muscles as they are would have sufficient strength
 to maintain it, though no doubt with less steadiness than
 those of man.   But the entire skeleton  and  many other
 points in the muscular system show conclusively that they
 never were designed to do any such  thing;  even with the
 great bulk of our extensors we find  it extremely tiresome
 to stand or walk with the limbs and trunk  semi-flexed,
 and that is the natural attitude  of  the ape, who is then
 principally supported by his  long arms,  the hands either
 resting on  the earth or grasping some object.   The pelvis
 of man is short and broad, the ischia being short and near
 together, allowing  the limbs to swing freely  by  them.
 The Glutceus  maximus lies about equally above and be-
low the socket or centre of motion.   But in the Quadru-
mana, and  in  most of the lower animals,  the ischia are
lengthened  and spread out, since the legs  do not swing
behind  them; the  Glutcei maximi arise  chiefly from the 
372
Contributions to the
 tuberosities, and are inserted generally much lower on the
 femur than in man, their increased length enabling them
 to contract through a longer space, and they are thus pow-
 erful retractors  of the whole  limb to  a certain extent,
 though not so as to  bring it into line with the trunk, how-
 ever strong they may be.  In man the external surface of
 the short, broad ilium looks outward like the acetabulum,
 and the fibres of the Glutceus medius converge from their
 broad origin to the great trochanter; the entire arrangement
 being such that the rnuscle acts to prevent the body from
 sinking to one side when supported by the opposite leg,
 and also, from the great breadth of its origin to assist  the
 Gluteus maximus and Psoas  in  preserving the  balance
 forward and  backward, which also is required  in ordinary
 progression.   But in the  ape the external surface of the
 ilium looks upward or backward, while the  acetabulum
 still looks outward as in man, thus at  right  angles with
 that surface; the ilia  are long and narrow,  so that  the
 fibres of the Glutceus medius run  nearly parallel  to each
 other, and the muscle is  inserted at the end, not, as  in
 man, down the outer side of the trochanter, upon which in
 the flexed state of the femur the muscle  acts as upon  the
 short arm of a lever of which the leg is the long arm ; just
 as in man when the femur is flexed, though to more ad-
 vantage, on account of its  attachment  to the tip of the
 trochanter.  It also tends to rotate the limb inward, which,
 when simple extension is  required, is counteracted by the
 simultaneous contraction  of the Glutceus maximus, which
 rotates  in the opposite direction.   It  appears, then, that
 the peculiar attitude of the ape is  not connected with the
 size  alone of the  Glutcei, but that since he was  not  de-
 signed to stand or walk erect, or  to rest on one  leg, his
 entire frame is constructed not for those, but for  another
 set of movements which are subsidiary in man, but to the
performance  of which both skeleton and muscles in the
ape are  perfectly adapted. 
Comparative Myology of the Chimpanzee.     373
  Quadriceps extensor femoris.  The Rectus has but a sin-
gle  tendon, from the inferior spinous process of the ilium,
the  tendon from the acetabulum  being absent, as in Ateles
Paniscus and  in a Macacus ;  this peculiarity is not  else-
where mentioned.  The Rectus  may act  as a powerful
flexor of the thigh,  in which  case  its extensor power is
easily counteracted by the flexors of the leg, which are in-
serted so low down as to act at even more advantage than
in man.   Both this muscle and  the scapular head of the
Triceps humeri, of which it is the homotype, are obviously
of more use to the ape as flexors than as extensors.
  To lessen the jar on striking the earth, and for the more
advantageous attachment of  muscles, the  limbs  of most
animals, especially those which move  quickly, are  con-
stantly flexed in two or three places  ; to support the weight
of the body without still greater  flexion, the extensors are
very thick and strong; in the elephant, however, whose
enormous bulk would require  supports of perhaps unman-
ageable size, the  limbs are  straight as in man;  but the
legs of the ape are constantly bent, and yet his exteasors
are not even so strong as in man, showing that the greater
portion of his weight must be supported  by  the  arms in
front.
  The employment of the ape's foot as an organ of pre-
hension requires an  extent and  freedom of motion at the
knee far  beyond that exercised  by  man;  the movements
must also be more  prompt and easily executed; this is
provided for by the low insertion of  the flexors on the tibia,
and by the length of the fleshy portion of the muscles, de-
priving the   Semi-Membranosus  and  Semi-Tendinosus of
the  characters which gave them their names in  Human
Anatomy.  The reverse is the case  in the leg of the com-
mon Quadruped, the Dog or the Cat; in them  the move-
ments are simply forward and  back, quick and  forcible,
but limited;  the muscles therefore  are  very  thick and 
374
Contributions to the
 strong, but  short, and the limbs  are  sharply bent  at  the
 joints.  But this mass of muscle about the limb would be
 wholly inconsistent with the motions of the prehensile foot
 of the ape,  or even a baboon, in whom therefore the mus-
 cles are  comparatively long  and slender.   The limbs of
 the Quadrumana are also projected further from the trunk
 than in the lower animals.  In  man the leg can be rotated at
 the knee only in a state of semi-flexion ; this is the constant
 attitude  of  the ape's leg, and the rotation  is very free.
 The short head of the Biceps would  act as an external
 rotator in the Anthropoids, but in the Mandrill I do  not
 think it exists, and in Quadrupeds generally it is  want-
 ing as such, though there is sometimes  a  slender slip from
 the pelvis.
  Sartorius.  Very  long, from  the great  height  of  the
 ilium ; it  is inserted by  a very short,  fascia-like tendon
 on the front of the  tibia, at least one third from the knee,
 over the Gracilis.   The Gracilis is  proportionally  much
 thicker and stronger than  in  man.
  Semi-membranosus.  Tendon of origin long, that of  in-
 sertion shorter, but attached as in man.  The tendon  of  the
 Semi-tendinosus joins that of  the Gracilis, and is inserted
 beneath it.  Biceps.   The long or ischiatic head is pro-
 portionally smaller  than in man, and  absolutely smaller
 than the Gracilis and  Setni-tendinosus.  The short head
 arises as in  man, and joins the other  at the knee, forming
 a very strong fascia which extends over the fibula nearly
to the ankle, the tendon of the long head sending a stron^
 prolongation to the outer tuberosity, as  in man.   The two
heads were  inserted thus together in  the  Chimpanzees  of
 Traill  and Vrolik, but separately in the  Gorillas of Wy-
man and Duvernoy,  and in Owen's Orang.   When on all-
fours, these  last three muscles would  also help retract the
leg; in a Cynocephalus the Biceps was  also  attached
 above the joint to the patella, and in the Dog, where the 
        Comparative Myology of the Chimpanzee.     375

motion  is simple retraction of the whole  limb, the Semi-
membranosus also is  inserted into  the  patella,  thus  giv-
ing a broader attachment, when the separate flexion of the
limb below the joint  is not required.  Like the  Glutcei,
these three muscles also serve to support the trunk on the
legs in one direction, while the Gracilis and Sartorius an-
tagonize them in front; their great size causes me to think,
as  in the case of the Glutcei, that  if the trunk could be
balanced they would  be able to maintain it erect, though
probably with not so much steadiness, on  account of the
heaviest part of the body being so far above the pelvis,
and not in and about it as in  man.  The  Popliteus is not
constant; in this  individual I think it was rather thicker
than in man, but I did not find the cartilaginous nodule  in
the external lateral  ligament where  the muscle arises.
Traill  and  Tyson could  not find the muscle, but it was
present in Vrolik's  Chimpanzee,  and  in  the  Gorillas  of
Wyman and Duvernoy.   Its action as a rotator inward
would be balanced by the short head of the Biceps, which
rotates outward.
   Gastrocnemius and Soleus.  These are much thinner than
in  man, but continue fleshy to their insertion ; the latter
has but one, the external head, as is generally the case  in
the Quadrumana.  The  two unite  at about two thirds
way down from the origins; the place of this union varies
in  different species, and often considerably in  individuals
of the same species; I do not  see that the place of union,
or the absence  of the internal head of the Soleus, would
have much effect upon the motions of the foot.
   Plantaris.  This was absent on the left side, and very
small on the right side of this Chimpanzee j it was present
in those of Vrolik and Tyson, but absent in that of Traill,
in the Gorillas of Wyman and Duvernoy, and in the lat-
ter's Orang, in the Howling-Monkey and Ateles Paniscus.
 Not constant in the Cynocephali. 
376
Contributions to the
  In man the Glutcei and long flexors of the leg have two
sets of functions according  as  they take their fixed point
from above or from below, that is, as they are used  either
for moving the legs by themselves as mere appendages, or
for  acting  powerfully upon the  trunk as in locomotion,
and  maintaining the erect  position on one or both legs.
In the ape, these positions not  being required, the muscles
are employed in locomotion and in leaping as we have
seen above, but chiefly  for moving the prehensile limb
with  any object which  may  be in its grasp ; they  are
therefore modified not so much in size as in position, in
which latter respect we remark the evidence as to the in-
tended semi-erect  attitude  of  these animals.  With  the
Gastrocnemius  and  Soleus  the case is otherwise.   They
also  perform two different functions  according as they act
from above or from below ; but in man their great strength
is  almost wholly employed after the  latter manner, for
raising and balancing the body upon  the foot, while  the
movements of the foot on the leg are limited, and require
little power.  The body  of  the ape is  not designed to be
balanced upon the foot in his usual attitude, and in walk-
ing he lifts the foot as a part of the leg without much mo-
tion at the ankle.  So in the ape the  Gastrocnemius and
Soleus are much more slender than in man, but their mus-
cular portion is longer, in adaptation to the less powerful
but more extensive  and  free movements of the prehensile
foot.  In most Quadrupeds, again, which rest on the ends
of the toes or  metatarsal bones, these muscles must be
powerful like the extensors  of  the other segments  of the
limb.  Thus we see  that the semi-erect attitude of the ape
is indicated by the modification as to position of the Glu-
tei and long flexors of the leg, but by a difference in size
of the extensor  muscles of the foot.
  Tibialis anticus.   This muscle is  thicker than in  man,
and continues fleshy lower  down.   In the Quadrumana 
         Comparative Myology of the Chimpanzee.     377

 generally, the division at the  insertion, of the  tendon
 into two parts is continued up so as to make two muscles
 more or less distinct.  In the Gorilla of Duvernoy this divi-
 sion existed only a little above the ankle, but in this Chim-
 panzee the two parts were distinct above the middle of the
 leg, and the posterior or internal portion which is attached
 to the internal cuneiform bone was three times as large as
 the other.  In Vrolik's specimen this portion arose upon the
 fibula.   The anterior portion which goes to the metatarsal
 bone is called by Prof. Wyman " Tibialis anticus minor,"
 and by Meckel " Abductor longus proprius pollicis pedis."
 The division evidently accords with the use of the great
 toe as a thumb.
   Peroneus longus and Peroneus brevis. These are not so
 distinct as in man.   The former would act as a flexor of
 the great  toe, which  enjoys  considerable  motion  at  the
 tarso-metatarsal articulation; there was a  sesamoid bone
 in its tendon as in man.  From the external  border of the
 tendon of the P.  brevis  near its insertion a slender  but
 strong fascia ran along the border of the metatarsal bone,
 and was connected  above the knuckle with what seemed
 to be a remnant of the extensor fascia of the  little toe.
   Extensor longus  digitorum.   Origin and insertion as in
 man.   In  Tyson's  Chimpanzee  there was  no tendon to
 the little toe, and in Owen's Orang none to the second
 toe.   I find that at the time of my dissection I made no
 note of the ligament described by Vrolik, through which
 run the tendons of  the Extensor  longus digitorum,  and
 now I  have no recollection of it, though I presume it was
 present; and Mr. Moore says  the muscle on the right side
 passed through a  separate loop just in front  of the astra-
 galus.   In a small Macacus now before me, the real annu-
lar ligament is attached to the  fibula higher than to  the
tibia, and not at all to the calcaneum ; and there  is also a
perfect  loop for the  Extensor digitorum, of which both
                 4 
378
Contributions to the
 ends are attached close together on the upper border of the
 calcaneum.  This loop  is one third  of an inch long, and
 freely movable after the fascia has  been taken away.   I
 should think that the .position of the annular ligament
 wholly above the joint, and of this  extra loop wholly be-
 low, would better enable the muscle  to act, not only as an
 extensor of the toes, but also more freely as a flexor of the
 foot, when also the insertion of the loop on the outer edge
 of the calcaneum would perhaps supply the  place  of the
 Peroneus tertius.
   Peroneus tertius.  So far as I know, this has been found
 in  the Quadrumana only once, in the  Howling-Monkey,
 by Prof.  Wyman, where,  however,  instead of  being a
 flexor of  the foot, it passed beneath the outer malleolus,
 and was inserted  into the base of the little toe, which it
 would serve to extend.
   Extensor proprius pollicis.   Probably present, though I
 neglected to make a note  of it;  on the right  side as in
 man.
   Tibialis posticus.  Origin and insertion apparently as
 in  man, but I  saw no sesamoid bone  near the insertion.
 In  Owen's Orang it was inserted into the internal cunei-
 form, and in Ateles Paniscus into the scaphoid  bone only.
 It is usually more slender than in man.
  Flexor  longus  digitorum.   Arises  as  in  man, but con-
 tinues fleshy to the ankle, below which it divides into two
 tendons, which are inserted into  the distal phalanges of
 the second  and fifth toes.  The Musculus accessorius is
 inserted into the  external border of this muscle, and from
 the tendon  arise  the  three fasciculi of  the  Lumbricales
 Flexoris longi digitorum.  The  disposition of the tendons
 of this muscle, and of the Flexor longus pollicis, is various
 in different individuals and species.
  Flexor longus  pollicis.  This is a  large, strong muscle
arising as in man and continuing fleshy to the joint, where 
Comparative Myology of the Chimpanzee.     379
  it forms a broad tendon which divides into three, which are
  inserted into the distal phalanges of the  first, third, and
  fourth toes, as in the Chimpanzees of Vrolik and Traill, and
  in  Duvernoy's Gorilla; the tendon  of the first toe passes
  through a separate strong loop at the base of the meta-
  tarsal bone.   In Owen's Orang the great  toe received no
  tendon from either of  the  long flexors, but in  the Howl-
  ing-Monkey the  great toe received the single  tendon
  of  the  Flexor  longus  pollicis.  In  dissecting the  Ateles
  Paniscus, both  Mr. Folsom and myself at first described
  this muscle as the Flexor longus digitorum, being deceived
  by its  great size, and  the number of its tendons.  The
  tendons of the  two muscles before their  subdivision are
  firmly connected by a  whitish substance.   As in Owen's
  Orang, bending the foot up against the leg  caused a me-
  chanical flexion of the toes which would materially in-
  crease the firmness of the foothold upon a branch.
   Flexor brevis  digitorum.  Arises as in man, but has  only
 two tendons, which are  inserted into the middle phalanges
 of the second and third  toes.
   Flexor accessorius.   Has but one, the  external head,
 which is joined to the outer border  of the Flexor longus
 digitorum.  Both this and the Flexor brevis vary consider-
 ably in different  species, and also in different Chimpanzees.
   Lumbricales Flexoris longi digitorum.   Three fasciculi
 arising upon the tendon of the Flexor longus digitorum;
 the  inner one is attached to the inner border of the  first
 phalanx of the second toe, the middle one joins the tendon
 of the Flexor brevis, to  be inserted  into the second pha-
 lanx of the third toe after being perforated  by the tendon
 of the Flexor longus pollicis, and the third or outer fascicu-
lus is also perforated by  a tendon of the same muscle,  and
is then attached to the second phalanx of the fourth toe.
  Lumbricales Flexoris  longi pollicis.  Also three  fasci-
culi  arising between and on both sides of the two tendons 
380
Contributions to the
of the Flexor longus pollicis, and  inserted into the inner
borders of  the bases of  the first phalanges of the third,
fourth, and fifth toes.   Thus  each toe  receives a  tendon
from a long flexor to its third phalanx,  the four outer toes
each a Lumbricalis  to the base of the first phalanx, the
second, third, and fourth  each a tendon from a  short flexor
to the second phalanx, and that of the third  toe  is also
joined by a tendon from a  long flexor ; the first and fifth
toes  having  peculiar short  muscles  of their own,  receive
fewest tendons from the  common flexors, and of the other
three the middle one is naturally best provided.  (See Table.)
  On the following Table, the  asterisks indicate the insertion of tendons
of the muscles named at the left, into the base of those phalanges of those
digits  against which they respectively stand; thus exhibiting the distri-
bution of the tendons of each  muscle, the tendons which  each digit re-
ceives, or the  tendons which are inserted into any one phalanx.
		'5		MAN.			TROGLODYTES				NIGER.	
MUSCLE.			to it		M tx		'5	to	"5	■Q	•rr c	
		-a	-5 1 ■5		•3 , -3 \ r3			■3	■a	•a	■3 ~ c	
		•^	* ! -=		J3	J3	.t,	—		J)	-a := M	
		r	e>» i co		*	*P'g	"	IN	ro	•<Ji	0 ""	
	' Flexor longus digi-		*P'gl*l)'Si*l>'g					*P'g			* 3d	
o	torum										2d	
,?, J											list	
4J \	Flexor longus pol-	*					*		*P'g	*P'g	3d	
a	licis										i 2d	
hJ	' Flexor brevis digi-											1st 3d
	torum		*p'd2	*p'd	*p'd	*p'd		*p'd	#p>d3			2d
u o												1st
K	Lumbricales Flex-											3d
<n .	oris longi digito-								*p'd	*p'd	2d	
■c	rum		*	*	*	*		*				1st
XI	Lumbricales Flex-											3d
1/1	oris longi polli-											2d
	k CIS								*	*	* 1st	
  From the above Table it will be at once remarked, that
in the human foot there are three muscles distributed uni-
formly to the corresponding phalanges  of the four lesser
  1 P'g=perforating.            2 P'd=perforated.
  « This tendon joins that of the Lumbricales Flexoris longi digitorum, and is
inserted with it. 
        Comparative Myology of the Chimpanzee.     381

digits, which latter also are of nearly equal power and im-
portance ; while in the foot of the ape, this uniformity does
not exist, and the digits are more independent of each other,
the middle one being the strongest, as in the hand of man,
in adaptation to the prehensile function of the member.
   The Interossei on the dorsal and plantar  surfaces were
not very distinct from each other, but the latter far exceeded
the former in size.
  Extensor brevis digitorum.   In the Quadrumana this con-
sists of only three fasciculi, supplying the second, third, and
fourth toes as in man, the fasciculus supplying the first or
great toe  being so distinct from the rest as generally to be
considered a separate muscle; this  is apt to  cause confu-
sion in  comparing dissections by different authors ; Traill
says the Extensor brevis digitorum  sent tendons to all the
toes, but Tyson says it was wanting altogether. (?)
   Extensor  brevis pollicis.   Forms  a distinct muscle in
most of the Quadrumana;  it is  inserted as in  man, but
has  a more oblique direction  on  account  of the  angle
which the great toe forms with  the side of the foot.
   Flexor brevis pollicis. Consists of two fasciculi  as in
man, the tendon of the Flexor  longus running between
them. I did not note the origin of the internal head which
is inserted with the  Abductor pollicis, but the external or
deep-seated  portion  appeared to  come from the internal
cuneiform and  partly from the metatarsal bone, and the
two heads were rather more  distinct than in  man.  Vrolik
describes but one fasciculus, but  generally there are two.
In Owen's Orang, the channel usually filled  by the tendon
of the long flexor was  occupied  by a small, short flexor
arising  upon the metatarsal  bone,  and inserted into the
first phalanx.
   Abductor  pollicis.  A strong muscle, arising, so far as
I could see, upon the  calcaneum alone,  and inserted as
in man with the internal head of the Flexor brevis, which 
382                Contributions to the
 indeed is far more closely connected with it than with the
 external head.  From the small size  and more outward
 position of the calcaneum, and  the  divergence of  the
 great toe, this  muscle would act rather as a direct flexor
 and adductor than as an abductor.   Vrolik says there was
 a smaller  fasciculus from the internal cuneiform, which
 perhaps represented the internal head of the Flexor brevis,
 of which he  says there  was but  a single head.  In  the
 Howling-Monkey the  Abductor consisted of  two parts,
 the one from the calcaneum being the  more  distinct, and
 acting as a flexor.
   Adductor pollicis obliquus.  Corresponds to the single
 muscle in  man, but is very much larger and more nearly
 transverse; it arises  as in man, and is inserted into  the
 first phalanx  of the  great toe, as in  Vrolik's  Chimpan-
 zee and in Duvernoy's Gorilla and Orang.  Traill makes
 no division into two, but seems  to include both this  and
 the Adductor transversus as one large muscle extending
 nearly the whole length of the second metatarsal. The Ad-
 ductor pollicis transversus appears to arise from the heads
 of the second, third, and fourth metatarsals, and is thinner
 than the preceding; it is attached  to all the bones of the
 great toe from the head of the metatarsal inclusive, as in
 Duvernoy's Gorilla and Orang.   Vrolik says it came from
 the fifth metatarsal.    The  Transversalis pedis is either
 unmentioned or declared absent by all the  authors,  ex-
 cepting perhaps Duvernoy.   There is none in this Chim-
 panzee, unless the Adductor transversus represents  it, as it
 certainly does  pretty nearly in position and action.
  Flexor brevis minimi digiti.   Has its origin and inser-
tion  as in man.  The Abductor minimi  digiti  arises as in
 man, but seems to consist of two not very distinct por-
tions, of which the internal is long and fleshy, and inserted
into the base of the second phalanx as in the  right foot,
 and as in Vrolik's  specimen;  while the external is small, 
         Comparative Myology of the Chimpanzee.     383

 and attached to the  base of the fifth metatarsal.  Neither
 Traill nor Tyson mention this peculiarity.
   Perhaps I can add nothing  to what has  been said by
 others, of the  great  contrast in  function, and thence in
 structure, between the extremities of man  and the ape.
 In the latter the hand is chiefly an organ of suspension,
 composed of four strong, flexible  hooks, which, even when
 the member is  employed as a hand, are flexed all together,
 the short, feeble thumb, so nearly in the same plane with
 them, not being opposable to the individual  fingers.  The
 foot is the organ of  prehension, being broad, the great toe
 standing out  as an  efficient thumb, with large and dis-
 tinct muscles ;  and even when  used simply for supporting
 the body on a  branch, the whole foot forms  a flexible tri-
 pod far more serviceable than the stiff narrow foot of man.

           WORKS EMPLOYED FOR COMPARISON.
   1.  Duvernoy, Prof.   Des Caracteres Anatomiques des
 Grands Singes Pseudo-Anthropomorphes. Deuxieme Me-
 moire.   Archives du Muse'um.   Tome VIII.  In Lib. of
 Harv. Univ.   (A very complete anatomy of the Gorilla.)
   2.  Edes, Robert T.  Dissection of a female  baboon.
 (Papio Maimon.)   MS. notes.
   3.  Moore, Joseph.  Dissection  of  the right side of the
 Chimpanzee, of which the left  side was dissected by Burt
 G. Wilder.  MS. notes.
   4.  Owen, Prof.  R.  Myology of  Simia Satyrus.  Pro-
ceedings of Zoological Society of London.  Jan. 25th and
May  10th, 1831.  Lib. Harv. Univ.
   5. Traill, Dr. T. S.  Observations on the Anatomy of
the Orang-outang, (Chimpanzee.)  Memoirs of the Wer-
nerian Nat. Hist. Society.  Vol. 3,  Feb. 7th, 1818.  Lib.
of B.  S. N. H.
  6. Tyson,  Dr. Edward.   Anatomy of a  Pigmy.  Lib.
Harv. Univ. 
384
Contributions, Sfc. '
  7. Vrolik, Prof. W.  Recherches D'Anatomie Compare
sur le Chimpanse*.   Lib. B. S. N. H.
  8. Vrolik, Prof. W.  Article " Quadrumana."   Todd's
Cyclopaedia of Anatomy and Physiology.   Lib. of B. S.
N. H.
  9. White, Dr. J.  C.  Dissection of a Mandrill.  MS.
notes.
  10. Wilder,  Burt  G.  Muscles  of a young male Chim-
panzee ; left side.  MS. notes.
  11.----Muscles of the fore-legs of a female  Angora
Goat.  Hind-legs of same, by Joseph Moore.  MS. notes.
  12. Wyman, Prof. J.  MS. notes.  Muscles of a young
Gorilla.
  13.----Muscles of a Cynocephalus, (arm.)
  14.----Muscles of a Howling-Monkey.
  15.----Muscles of a young Chimpanzee.   Proceedings
of Bost. Soc. Nat. Hist.   Vol. 5, Nov. 21st, 1855.  Lib.
of B. S. N. H.
  16. MS.  notes more or less complete on two  Cyno-
cephali, three Macaci, and  an Ateles  Paniscus, dissected
by Norton  Folsom, J. S. Lombard, Joseph  Moore, Wil-
liam Nichols, Jr., and Burt G. Wilder.   1861. 
 
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