SEALS. 509 



family of Seals with true single-rooted molars ; the formula of this 

 genus, is: 



Incisors — ; canines — : premolars — ; molars — : == 34. 



2-2 ' 1_1 ' r 3_3 > 2-2 



The four middle upper incisors are close set, with pointed recurved 

 crowns; the lateral incisors are much larger and laniariform: the canines 

 have moderate crowns, with a sharp ridge before and behind. The 

 crowns of the molar teeth (PI. 132, fig. 5) are conical, subcompressed, 

 longitudinally and finely grooved, with an anterior and posterior edge ; 

 those below have generally a slight notch at the fore and back part of 

 the base. The first molars, both above and below, are the smallest, 

 with a simple crown and a single ventricose fang ; the second and 

 third above, and the second, third, and fourth below, have two 

 connate roots ; the two roots are commonly distinct in the remaining 

 posterior molars : all the roots are very thick. 



In the genus Otaria (ib. fig. 6) the dental formula, is : 



Incisors — : canines — : premolars — : molars — = 36. 



2—2 ' 1—1 ' •• 3—3 ' 2—2 



The two middle incisors are small, subcompressed, with the crown 

 transversely notched ; the simple crowns of the four incisors below fit 

 into these notches : the outer incisors above are much larger with a 

 long pointed conical crown, like a small canine. The true canine is 

 twice as large as the adjoining incisor, and is rather less recurved. 

 The molars have each a single fang; the crown is conical, sub- 

 compressed, pointed ; in the two last recurved, with a basal ridge or 

 *cingulum,' broadest within: in the Otaria jubata, with a pointed 

 cusp developed from its fore-part, and in the last two molars also 

 from its back part. In some species, as the Otaria lobata, {Phoca 



out as distinguishing the Sten, serridens from the Sten. Ipptonyx, except the above-cited variety 

 respecting the implantation of the premolars ; and even this is misinterpreted, the supposed 

 single root being essentially two roots connate. A re-examination of the specimens of <S/e«. 

 serridens, in comparison with Sten. leptonyx, has only impressed more strongly the truth of the 

 observation with which I concluded my description of that new species, " the modifications of 

 the compressed and deep-cleft molars are not of sufficient importance to justify the introduction 

 of a new generic name into the group of amphibious or pinnigrade Carnivora, which has already 

 been overburthened in this way."(a) 



(a) Annals of Nat. History, 1843, p. 331. 



