xii PHYLUM CHORDATA 543 



of forwards as in other mammals ; the five digits of the foot 

 are all provided with claws. So complete is the adaptation 

 of the limbs to the purpose of flight that bats are only able 

 to shuffle along with great difficulty on the ground, though 

 with the aid of their claws they are able to climb and to 

 suspend themselves from branches of trees by the hind-feet. 



In the lemurs and their allies (Prvsimii) the body is 

 slender, and the limbs adapted for an arboreal existence. 

 The hallux is divergent from the other digits of the foot 

 and opposable to them, and the same holds good, in some 

 cases, of the pollex. In some, all the digits are provided 

 with claws, or all but the hallux. More commonly all the 

 digits are provided with flat nails, except the second of the 

 pes, which always has a claw. The eyes are very large. 

 The muzzle is sometimes elongated, sometimes short ; the 

 nostrils are slit-like. The tail is sometimes absent or short ; 

 more usually it is greatly elongated, but it is never prehen- 

 sile. The surface is always covered with soft fur. 



Of the remaining groups of Primates the Hapilidae or 

 marmosets are small squirrel-like animals with all the digits 

 except the hallux provided with pointed claws, with the 

 pollex incapable of opposition, the tail non-prehensile, and 

 without cheek-pouches or callous patches over the ischia. 

 The Cebidae, or American monkeys, resemble the Hapalidae 

 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 Cercopithecidae, or baboons and macaques, 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 



