1422 



CLASS MAMMALIA. 



-ot- 



clavicle is never complete, and is frequently absent ; the radius and 

 ulna and the tibia and fibula are always distinct ; but the scaphoid 

 and lunar of the carpus very frequently coalesce. In a large num- 

 ber of cases the humerus has an entepicondylar foramen. The 

 majority of the species subsist on animal food. In the more spe- 

 cialised types there is a tendency to a reduction in the number of 

 the cheek-teeth, more especially the true molars. 



As in the Rodents and the following orders, the manus is sus- 

 ceptible in most cases of the movements of pronation and supina- 

 tion ; the head of the radius being ac- 

 cordingly freely movable in the lesser sig- 

 moid cavity of the ulna. The proximal 

 extremity of the latter bone is shown in 

 the accompanying woodcut in order to 

 exhibit the characteristic features obtain- 

 ing in the unguiculate orders. Some 

 observations on the phylogeny of the 

 order will be found under the head of 

 the Creodonta. 



The Carnivora are divisible into the 

 suborders Pinnipedia, Carnivora Vera, 

 and Creodonta ; the latter being the most 

 generalised. 



Suborder i. Pinnipedia. — This sub- 



i'W§ r' /'-jf order comprises the typical Seals (Pho- 



j'lji' J/ cidcz), the Walruses {Trichechidcz), and 



| If ; i jij the Eared, or Fur, Seals (Otariidce) ; all 



of which mainly differ from the typical 

 Carnivora in points connected with their 

 subaquatic life. The brain is relatively 

 large, with its hemispheres much convo- 

 luted, and broad in proportion to their 

 length. The limbs are short, and are 

 each furnished with five digits, which are connected by a web : in 

 the hind feet the first and fifth digits are stouter, and generally 

 longer, than either of the others. In the Phocidce the hind feet 

 when walking are directed backwards parallel to the axis of the body, 

 but in the Otariidce, which are the. least aberrant members of the 

 suborder, they are turned forwards. The dentition varies, but at 

 least three kinds of teeth are always present. The canines are long 

 and pointed ; the cheek-teeth (fig. 1301), which usually comprise four 

 premolars and one true molar, are not differentiated into carnassials 

 and tuberculars, but are usually sharply pointed and often furnished 

 with fore-and-aft basal cusps, although they are blunt and rounded 

 in the Walrus. There is always a diminution of the incisors below 



-sig.. 



l-sig 



Fig. 1300. — Anterior aspect of the 

 proximal extremity of the right 

 ulna of Hy&narctus; from the Si- 

 walik Hills. Reduced. ol, Ole- 

 cranon ; a, Anterior tubercle of do. ; 

 sig, Sigmoid cavity ; Lsig, Lesser 

 do. for head of radius. 



