256 VERTEBRATA. 



extinct. Other members of the order are the dugongs (Halicore 

 australis and H. indica) and two or three species of manatee or 

 sea-cow (Manatus). Halitherium and Prorastomus are from the 

 Tertiary deposits ; the latter had canine teeth in both jaws. 



In the recent works of Glaus and Schmarda this group is not 

 separated from the Cetacea. Cope's Homodonta include these 

 orders and the Edentata. 



Manatida. Ehytina. 



Halicore (Dugong). *Halitherium. 

 Manatus. *Prorastomus. 



Order XII. PINNIPEDIA. 



Limbs fin-like ; the posterior horizontal, directed backwards. 

 Three kinds of teeth. Mammas two or four, ventral. 



The toes are entirely enveloped in the integument, and almost 

 the only indication of their presence is their strong claws. The 

 hind limbs, from their horizontal position and their close con- 

 nexion with the tail, form the principal organ of progression in 

 the water. On the land they move by a shuffling on of the body 

 or by short leaps. 



The teeth vary in number according to age ; the incisors are 

 nearly all deciduous after a time. The lips are fleshy, furnished 

 with long bristles, and the nostrils are capable of being closed by 

 a peculiar sphincter muscle. The brain is large. There are no 

 clavicles. 



Owing to the peculiar structure of the vena cava, the blood 

 finds its way back to the lungs so slowly as to check the respiration, 

 and so enables the animal to remain a considerable time under 

 water. 



The male of the sea-elephant (Cystophom proboscidea) has a 

 muscular sac at the tip of the nose, which it can inflate at plea- 

 sure ; a somewhat analogous appendage is placed on the head of 

 Stemmatops cristata. 



The common seal (Phoca vitulina) and the grey seal (Halichoerus 

 gryphus] are the only species that can be said to inhabit these 

 islands. Others have been mentioned, but they are either strag- 

 glers or doubtful ; among them are the harp-seal (Phoca gr&n- 

 landica) and the walrus (Trichechus rosmarus). 



Pinnipedia are by some regarded as a suborder of Carnivora ; 

 Glaus and Schmarda rank it as an order. Two very distinct 

 families are included. The eared seals (Otarice) are by some 



