PINNIPEDIA. RODENTIA. 627 



are absent, and the angle of the mandible is not inflected. The tympanic 

 bullae and mastoid processes are large. The skull in many of its fea- 

 tures recalls the cetacean type. Dentition, i f^ c -}- p and tn 4 ; the 

 canines are well developed ; the milk molars appear to be |, and are some- 

 times shed during foetal life. There is no scrotum, and the testes are 

 abdominal or just outside the inguinal canal. 



Locomotion on the land is effected by a wriggling of the trunk, with 

 or without the assistance of the forelimbs. They are inoffensive crea- 

 tures and mostly gregarious and polygamous. They are exceedingh^ 

 intelligent and docile, and in captivity attach themselves to man. It is 

 said that in some species the young do not readily take to water, and 

 have to be taught to swim. When born they have a thick soft fur, which 

 falls off before they enter the water. They are much hunted for their 

 skins and oil. 



There are 9 genera and about 15 species, principally confined to the 

 Arctic and Antarctic seas, but found in intermediate areas. Most of 

 them ai"e marine, but a few ascend rivers and are found in inland seas and 

 lakes, as the Caspian and Lake Baikal. Their remains, not numerous, 

 are known fossil from the Miocene onwards in Europe and N. America. 



Sub-fam. 1, Phocinae. i #, feet with well-developed claws, 

 digits of pes sub-equal with membrane not extending beyond the 

 toes. Halichoerus Nils., 1 sp. H. grypiis, the grey-seal of the 

 British Isles, attains to 8 feet in length, Atlantic. Phoca L., 6 species, 

 X. Hemisphere ; P. vitulina, the common seal, British Isles, 4 to 5 

 feet in length, ascends rivers, Arctic Ocean, N. Atlantic and Pacific ; 

 P. caspica, Caspian and Aral Seas ; P. sibirica. Lake Baikal ; P. 

 groeenlandica. 



Sub-fam. 2. Monachinae. i f , the outer digits of the pes exceed 

 tiie others in length, with small or absent nails. Monachus Flem., 

 1 sp. M. albiventer, monk-seal of the Mediterranean and Atlantic. 

 Ogmorhinus Pet., 1 sp. 0. leptonyx, the sea-leopard, Antarctic and 

 southern temperate seas ; Lobodon Gray, 1 sp., Antarctic Ocean. 

 Leptonychotes Gill., 1 sp.. Ant. Ocean ; Ommatophoca Gray, 1 sp., 

 Ant. Ocean. 



Sub-fam. 3. Cystophorinae. i t, outer digits of pes longer than 

 the others, nails small or absent. Cysiophora Nils., 1 sp. C. cris- 

 tata, hooded or bladder-nosed seal of the N. Atlantic, occasionally 

 visits the British coasts : %vith a dilatable sac upon the face. Macro- 

 rhinus F. Cuv., the elephant seal ; nose produced into a short pro- 

 boscis capable of dilatation, 1 sp., M. leoninus, the sea-elephant, 

 attaining a length of nearly 20 feet, Antarctic Ocean and N. Pacific 

 (California). 



Order 18. RODENTIA* (GLIRES). 



Usually plantigrade animals ivith a pair of large shar^) 

 chisel-shaped rootless incisors in each jaw and without canines. 

 The grinding teeth are either lophodont or hunodont; the articular 

 surface for the lower jaw is nearly always longitiidinally elon- 



* Waterhouse, Natural History of the Mammalia, vol. 2, 1843. Brandt, 

 Die cranioloijischen Entwickelunas-stufen u. Class, der Nager der Jet/ 



