462 FAMILY PHOCID^E. 



1. Muzzle narrow, regularly declined. Incisors |^|> simple, conical; mo- 

 lars, except first, 2-rooted, and mostly 3-lobed. Digits of manus 

 slightly decreasing in length from first to fifth, or first and second 

 subequal. Mamnise 2 Phoca. 



a. Skull broad, massive; general form thick; the limbs short; nose 

 broad. Molar teeth large, crowded, obliquely implanted, especially 

 in youth and in the lower jaw. Nasals considerably prolonged pos- 

 teriorly. Posterior nares narrow, the septum incompletely ossified. 

 Palatines deeply emarginate. Scapula sickle- shaped, the post-scap- 

 ular fossa greatly developed (Subgenus) Phoca. 



ft. Skull thin, light; nose pointed, and general form slender. Teeth 

 small, slightly separated. Palatines, posterior nares, and narial 

 septum nearly as in the subgenus Phoca. Nasals less prolonged 

 posteriorly. Digits of pes subequal. Scapula nearly as in Phoca. 



(Subgenus) Pusa. 



c. Skull, teeth, and general form nearly as in the subgenus Pusa. Pos- 

 terior nares broad (nearly twice as broad as high), the narial sep- 

 tum complete. Palatines truncate, or slightly emarginate ; never 

 deeply so as in Phoca and Pusa. Scapula nearly as in the typical 

 terrestrial Ferae not sickle-shaped, and with a broad pre-scapular 

 fossa. Sexes, when adultj widely different in coloration. 



(Subgenus) Pagophilus. 



*2. Muzzle broad; forehead convex. Rudimentary supraorbital processes. 

 Dentition weak ; the molars much separated, slightly implanted, 

 and partly deciduous or abortive in old age. Palatines broad, 

 emarginate. Middle digit of niauus the longest. Limbs small. 

 Scapula with no acromion process. Whiskers smooth, attenuated. 

 Mammse 4 Erignathus. 



3. Cranial characters unknown. Dental formula as in Phoca. Molars, 



except the first, 2-rooted, somewhat separated, with the crowns 

 simple and directed backward, as in Halichcerus. Sexes, when 

 adult, widely different in color Histrioplioca. 



4. Muzzle broad; skull much arched, increasing in height anteriorly. 



Molars single-rooted, except the last lower and the last two upper, 

 nearly simple or 1-lobed, conical. Whiskers crenulated. Digits of 

 manus as in Phoca Halichoerus. 



5. Muzzle elongate, depressed ; nasals, short ; skull somewhat depressed 



posteriorly. Incisors |^|, notched transversely on the inner side of 



the crown. Canines large. Molars thick, strong, obliquely and 

 closely implanted, imperfectly lobed, and only the three posterior 2- 

 rooted. Whiskers flat, smooth, tapering. Claws small, especially 



those of the pes Monachus. 



II. Zygpmatic process of the maxillary and the malar bones nearly as in 

 the Phocinw. Intermaxillaries not prolonged to meet the nasals. 

 Nasals very small. Supraorbital processes distinct, prominent, but ' 



Small. Incisors ^f . Molars simple or plaited, not lobed, with a 



single club-shaped root CYSTOPHORIN2E. 



6. Palatines short, slightly emarginate, somewhat arched or vaulted. 



Auditory bullae square in front. Adult males with an inflatable 

 sack extending from the nose to the occiput. All of the digits with 

 claws strongly developed Cystophora. 



