484 THE ASTATOMT OF VEETEBEATED ANIMALS. 



In Hylohates, the tendon of fhe flexor perforans pedis goes 

 only to tlie fiftli digit, and is not directly connected with 

 that of the fl.exor longus hallucis, -which supplies the other 

 foui" digits. In the Orang, also, the tendons of the two 

 muscles are separate ; but the flexor perforans supplies the 

 second and the fifth digits, and the/ea;or hallucis the third 

 and foiu'th. It gives no tendon to the hallux. In both 

 the Chimpanzee and the Goi-illa, a very large tendon is 

 given to the hallux by the flexor hallucis, and it also supplies 

 the third and foui-t.h digits. The tendon of flexor longus 

 digitorum is but slightly connected with that of the^ea;or 

 hallucis, and its divisions go to the second and fifth toes. 

 In both the manus and the pes of Hylobates a muscle occurs 

 which is not, at present, known in any other Mammal. It 

 arises from the second metacarpal or metatarsal bone, and 

 is inserted by a long tendon into the pre-axial side of the 

 ungual phalanx of the second digit ; it may be termed " ab- 

 ductor tertii internodii secundi digiti." 



The Oi^ang, in like manner, stands alone in possessing a 

 small, but distinct opponens hallucis.* 



The voliime of the brain, in the Orang and in the Chim- 

 panzee, is about twenty-six or twenty-seven cubic inches ; or 

 about half the minimum size of a normal human brain. In 

 the Goi-illa, the volume rises to near thii-ty-five cubic inches. 

 In the Gibbons the brain is very much smaller; and the 

 Siamang, among these, is remarkable for the short posterior 

 lobes of the cerebi-um, which, in this anthropomoi-phous Ape, 

 do not overlap the cerebellum, as they do in all the others. 



The cei'ebral hemispheres are higher in proportion to 

 theii' length in the Orang than in the other Anthropomorpha ; 

 but, in all, they are elongated and depressed, as compared 

 with those of Man. The frontal lobes taper off anteiiorly, 

 and their inferior surfaces are excavated from without 

 downwards and inwards, in con'espondeace with the pro- 



* It must be borne in mind that these statements respecting the 

 myology of the Anthropomorpha are based upon Tay own dissections 

 (sometimes supplemented by those of Duvernoy and other ana- 

 tomists) of particular specimens. Endless varieties will no doubt be 

 met with by those who carry their inquiries further. 



