478 ZOOLOGY SECT, 



plicated by the presence of an inner lobe or tragus, and often pro- 

 duced into remarkable arborescent appendages, and the nose also 

 often provided with elaborate leaf-like or arborescent lobes. The 

 surface is usually covered with soft fur, except in one group of 

 Microchiroptera in which the integument is practically naked. 

 The tail is sometimes short, sometimes well developed ; in the latter 

 case it may or may not be involved in the tail-membrane. 



In the Lemurs and their allies (Prosimii) 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 prehensile. The 

 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 Cebiclse resemble the Hapalidaa 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 Cercopithecids& 

 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, 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 fore-limbs acting as crutches 

 is necessary to enable the animal to swing itself along. 



Endoskeleton. The spinal column of Mammals varies in the 

 number of vertebrae which it contains, the differences being mainly 

 due to differences in the length of the tail. The various regions 

 are very definitely marked off. In the cervical region the first two 

 vertebrae are modified to form the atlas and axis. Owing to the 

 absence of distinct cervical ribs, the posterior cervical vertebrae 

 are much more sharply marked off from the anterior thoracic than 



