tt Luwer jaw strony, icith an acute angle ; orbits ?noderafe. 



4. Stenorhynchus. Skiill aud muzzle elongate ; griuders compressed, 

 with tliree cylindrical elongated lobes, the centre one longest and 

 largest. 



6. MoNACHUs. Skull broad, depressed behind ; muzzle short, broad ; 



orbits lax'ge ; giinders small, conical, thick, with a small anterior and 

 posterior lobe ; lower jaw broad, vnth. a distinct posterior angle ; 

 upper cutting-teeth transversely notched ; palate angularly notched 

 behind. 



b. Cutting-teeth | ; the first grindei' in each jaw single-rooted, the rest 



two-rooted; muzzle bald, callous hetioeen and above the nostrils, and 

 divided by a central groove ; wrist rather exserted ; fingers subequal ; 

 claivsfive, large. Phocina. 



* Branches of loiver jaw diverging; Imuer edge of lower jaw rvimdedf 



simple; palate angularly arched behind; angle of loicer jaw blunt, 

 sloping behind. 



G. Callocephalus. Muzzle rather narrow ; whiskers waved ; toes gra- 

 dually shorter ; web between the hind toes hairy ; hair subcylindrical ; 

 under-fur thin. 



*• Branches of lower jaw diverging; lowo' edge of loicer jaw dilated on 

 the inner side. 



7. Pagomys. Palate angularly notched behind ; angle of lower jaw 



blunt, sloping behind. 



8. Pagophilus. Palate truncated behind ; angle of lower jaw acute, 



erect behind, with a notch above the basal tubercle ; muzzle rather 



Eroduced ; whiskers waved ; toes gradually shorter ; web between 

 ind toes baldish ; hair dry, flat, close-pressed, without any imder- 

 fur. 



*** Branches of lotverjaiv arched on the side and wide apaii, ; lower edge 

 produced on the inner side behind the symphysis ; palate arched. 



9. Halicyon. Tubercle on inner edge of front part of lower jaw elon- 



gate, sharp-edged ; teeth moderate ; angle of lower jaw simple, with 

 a distinct notch above it. 



10. Phoca. Tubercle on inner edge of front part of lower jaw blunt, 



rugailose ; teeth small ; angle of lower jaw with a roimded lobe on 

 inner side above the basal tubercle ; muzzle broad, short ; forehead 

 convex ; whiskers smooth, simple ; ear-hole large ; fingers unequal, 

 the third longest, second and fom-th long, the first and fifth shorter, 

 neai'ly equal. 



B, Grinders with single root (except the two hinder grinders of Hali- 

 choerus). 



c. Ears without any conch; toes simple, of fore feet exserted, of hind feet 



large, the inner and aider ones large and long, the three middle ones 

 shorter ; palm and sok'S hairy, sometimes chaff)/ and callous from 

 wear; nntfile hairy to the edge and between the no^rils. 



* 3ftizzle large, truncated, simple; canines large; grinders lobed, ivhen 



old truncated. Trichechina. 



11. IIai.ichcerus, Muzzle broad, rounded; cutting-teeth 'I ; grinders |^, 

 conical, the two hinder of the upper and hinder one of the lower jaw 



