SYNOPSIS OF SUBFAMILIES AND GENERA. 461 



certainly monotypic, and if the other two are not also mono- 

 typic, the species respectively comi^osing them have not as 

 yet reached the point of well-pronounced specific divergence 

 nor of geographic isolation. As regards the Phocids, we have 

 already seen that in nearly every instance each species has been 

 made the type of a distinct genus. Conservative writers, how- 

 ever, agree in referring four species {vitulina, grcenlandica^foetida^ 

 harbata) to the genus Plioca {Callocephahis, F. Cuvier), yet each 

 species differs from the others to such a degree in cranial 

 and other imj)ortant osteological characters that, if we allow 

 to such difierences the value usually accorded them among 

 the terrestrial Fercc, each of these species may be regarded 

 as the type of a distinct subgenns, or even genus. In the 

 present revision I feel constrained to separate the Plioca harbata 

 of authors as generically distinct from the other species of the 

 restricted genus Phoca, and to associate with the remaining 

 species Phoca caspica and Phoca sibirica. The Phoca fasciata 

 of authors ( = equestris, Pallas) Gill has made the type of his 

 genus Sistriophoca. The species is remarkable for its peculiar 

 pattern of coloration, and von Schrenck compares its dentition 

 to that of Halichoerus, between which and the ordinary Phocce 

 it holds an intermediate position as regards the structure of the 

 molar teeth. The other genera of the Phocids will be provision- 

 ally received as now commonly accepted. Monachus stands 

 widely aloof from the other genera of the Phocinw, with which, 

 however, it seems more closely allied than with any of the gen- 

 era of the Stenorhynchince, although all of these have been re- 

 ferred by some systematists (as Wagner and Giebel) to a single 

 genus under the name Leptonyx. Without feeling sure that 

 the Phocids are susceptible of subdivision into trenchantly- 

 marked subfamilies, or into groups really entitled to such rank, 

 they will in the present connection be provisionally adopted in 

 their current acceptation. 



Synopsis of Subfamilies and Genera. 



I. Zygomatic process of the maxillary with the posterior border subvertical, 

 not extending far backward beneath the malar ; the latter short. 

 Intermaxillaries prolonged upward, meeting the nasals. Nasals 

 long, nearly reaching to the middle of the orbits, greatly narrowed 

 posteriorly, and wedged between the frontals. Supraorbital pro- 

 cesses wholly obsolete or (in Erignathus) rudimentary. Interorbital 



region very narrow. Incisors usually oZli^ exceptionally (in Mo- 



nachus) ^^^' Nails of all the digits well developed ; outer digits of 

 the pes not much prolonged beyond the others PHO CIN.3i. 



