XIII 



PHYLUM CHORDATA 



557 



inner surfaces, and for the shortness of the pubic symphysis. In 

 the higher Apes some of these features are recognisable, though 

 less pronounced ; but in the lower the ilia are long and narrow, and 

 usually curved outwards ; in the Old-world Monkeys the tuberosities 

 of the ischia are strongly everted and roughened for the attachment 

 of the ischial callosities. 



The tibia and fibula are well-developed and distinct in all. In 

 nearly all, the hallux, owing to the form and direction of the articu- 

 lation between it and the internal cuneiform, is opposable to the 

 other digits, converting the foot into a grasping organ. The 

 human foot (Fig. 1180) is distinguished from that of the other 



Man 



Fin. 1180. Foot of Man, Gorilla and Orang drawn the same absolute length, to show the 

 difference in proportions. The line a' a' indicates the boundary between tarsus and meta- 

 tarsus ; V b', that between the latter and the proximal phalanges ; and c' c' bounds the ends 

 of the distal phalanges, as. astragalus ; ca. calcaneuni ; sc. scaphoid. (After Huxley.) 



Primates by the absence of .this power of opposition and by 

 the relative length of the tarsus, which exceeds that of the 

 metatarsus. 



Digestive Organs. Teeth are present in nearly all Mammals, 

 but in some they are wanting in the adult condition (e.g., Whale- 

 bone Whales and Platypus). In Echidna teeth are not present 

 even in the young. In some of the Anteaters teeth are developed 

 in the foetus and are thrown off in utero the adult animal being 

 devoid of them. 



VOL. II 



M M 



