
THE CHIMPANZEE AND ORANG UTAN. 365 
at the lower part, for the insertion of muscles” in the ulna of his specimen of Simia 
Satyrus, This process is less marked in younger specimens, but is very obvious in the 
skeleton of the Pongo. It serves for a more advantageous attachment to the pronator 
quadratus, which muscle has greater breadth than in Man. The length of the radius to 
the ulna is in Man as 11 to 12; in the Orang it is as 36 to 37. 
The bones of the hand, like those of the fore arm and the humerus, recede from the 
human type in their elongated form ; the bones of the thumb, however, are very slen- 
der and short, and do not reach to the end of the metacarpal bone of the fore finger. 
The bones of the carpus have their ossification completed later than in the human sub- 
ject, and allow of a freer motion upon each other. The os pisiforme is divided into 
two, so that the number of carpal bones is nine. The proximal phalanges of the fingers 
are more curved than in Man, and the lateral ridges more strongly developed than in 
the Chimpanzee. The distal phalanges are more pointed, not expanding at their extre- 
mities to give support to an extended surface of delicate touch. 
As the upper extremities exceed in length those of the Chimpanzee, so the lower ex- 
tremities differ as much in the contrary respect, preserving throughout the existence of 
Simia Satyrus much less than the fully grown foetal proportions of the human subject. 
The femur has a straight shaft, but differs from the human chiefly in having no de- 
pression on the head for a ligamentum teres!. The neck is shorter and forms a more ob- 
tuse angle with the shaft of the bone, and there is not any linea aspera at the posterior 
‘In three recent specimens of Simia Satyrus I have found the ligamentum teres deficient in both the hip- 
joints. This singular circumstance in the organization of the Orang Utan is not noticed in the Manuals of 
Comparative Anatomy of Blumenbach or Cuvier, although it has been recorded by Camper in his Treatise 
on the Orang. (See Ciuvres, tom. i. p. 132.) It appears also to have been overlooked in the dissection of 
the Orang detailed by Dr. Jeffries (Boston Journal of Philosophy, vol. ii. p. 570; Philosophical Magazine, 
vol. Ixvii. p. 186.), unless, from the inference which he draws, the hip-joint of his specimen really presented 
this remarkable exception to the general structure. He says: ‘‘ The articulation of the femur with the acetabulum 
is almost exactly like Man’s; the neck of the bone forms about the same angle. In quadrupeds this forms a 
distinguishing characteristic, being in them nearly a right angle: the inspection of this joint is alone sufficient 
to satisfy the naturalist of at least the facility, if not the natural disposition, of the Satyrus to walk erect”! 
The skeleton is doubtless still preserved, and it would be worth while to make a re-examination of the head of 
the femur to ascertain the presence or otherwise of the depression for the ligamentum teres. 
In all the other Quadrumana which I have examined the ligamentum teres is present, but in none of them are 
the legs so disproportionately short as in the Orang; the deficiency of the ligament doubtless, therefore, bears a 
relation to this circumstance, and a greater flexibility of the hip-joint, especially of rotation inward, is the result. 
In the Unau (Bradypus didactylus, Linn.) and Ai (Brad. tridactylus, Linn.), with hinder limbs of similar pro- 
portions to those of the Orang, and habits still more strictly arboreal, a similar extent of motion is allowed to 
the leg by the absence of a restraining ligament in the hip-joint. 
In the Elephant and Megatherium the deficiency of the ligamentum teres would seem to relate to the position 
of the acetabulum with reference to the head of the femur, the socket resting upon the ball, and not receiving 
it obliquely sideways, as in most other quadrupeds. 
In the Manis didactyla, in the Seal, and in the Walrus, the ligamentum teres is wanting. Rudolphi and 
VOL, I. 3c 
