SEALS. 507 



there are two small cusps behind the principal one, and in the three 

 or four posterior molars in the lower jaw there are sometimes two 

 small cusps before and two behind the principal one.(l) 



In the Phoca caspica the upper molars have commonly one ac- 

 cessory cusp before and one behind the principal lobe, the lower 

 molars have one accessory cusp before and two behind the lower 

 molars. 



In the Phoca grcsnlandica the upper molars have no anterior basal 

 cusp and only one behind ; the lower molars have two cusps behind 

 and one in front, except the first which resembles that above and, 

 like it, has connate fangs. 



The condition of the molar teeth is nearly the same in the 

 Phoca barbata (PL 132, fig. 2) ; but the crowns are rather thicker and 

 stronger, and the three middle ones above have two posterior basal 

 cusps feebly indicated, the same being more strongly marked in the 

 four last molars below. 



The following genera of Seals with double-rooted molars, {Pela- 

 gius & Stenorhynchus) , have four incisors above as well as below, 

 i. e. lEf. An upper view of the molar teeth in the Hooded Seal of the 

 Mediterranean, Pelagius monachus, is given in PI. 132, fig. 3, as when 

 they are worn down in an old specimen ; the crowns are thick, obtuse, 

 subcompressed, with a well developed cingulum, a principal lobe and 

 an anterior and posterior accessory basal lobule; the fangs are connate 

 in the first tooth both above and below. 



The allied sub-genus {Ommatophoca) of Seals of the southern 

 Hemisphere has six molar teeth on each side of the upper, and five 

 on each side of the lower jaw, with the principal lobe of the crown 

 more incurved. The two first molars above are closely approxi- 

 mated ; but this may prove to be a variety. 



In the Stenorhynchus the jaws are more slender and produced, 

 and the molar teeth are remarkable for the long and slender shape of 

 the principal lobe and of the accessory basal cusps. The incisors 

 have sharp conical recurved crowns, like the canines, and the exter- 



(1) Nillson, in Wiegraann's Archiv. 1841, p. 313. I notice these varieties of the crown, in 

 connection with analogous ones in the fangs of the teeth of the same species, to show the inade- 

 quacy of such characters as marks of subgeneric distinction. 



