XIII 



PHYLUM CHORDATA 



509 



The 



usually it is greatly elongated, but it is never prehensile, 

 surface is always covered with soft fur. 



Of the Anthropoidea, the Hapalidse or Marmosets are small, 

 squirrel-like animals with all the digits except the hallux pro- 

 vided with pointed claws, with the pollex incapable of opposition, 

 the tail non-prehensile, and without cheek-pouches or callous 

 patches over the ischia. The Cebidse resemble the Hapalidse in 

 the negative characters of the absence of ischial callosities and of 

 cheek-pouches, and of the power of opposition in the hallux. But 

 the limbs are much longer, the digits are all provided with flat 

 nails, and the tail is frequently prehensile. The Cercopithecidse 



FIG. 1124. Gorilla. (From the Cambridge Natural History.) 



all have brightly-coloured, bare, callous patches of skin (callosities) 

 over the ischia, and most of them have cheek-pouches for the 

 storage of food. All the digits are provided with flat nails. The 

 tail may be long, or short, or absent; when present it is never 

 prehensile. The pollex, when developed, is always opposable to 

 the other digits. In the Simiidse or Man-like Apes (Fig. 1124) 

 a tail is never developed, and there are no cheek-pouches; ischial 

 callosities are present only in the Gibbons. The Gibbons can 

 walk in an upright position, without the assistance of the fore- 

 limbs; in the others, though, in progression on the surface of the 

 ground, the body may be held in a semi-erect position with the 

 weight resting on the hind-limbs, yet the assistance of the long 



