** The front grinders of each jaw single-rooted, the rest two- 

 rooted. 



-2. STENORHYNCHUS. Skull elongated; muzzle elongate; 

 grinders compressed, with three cylindrical elongated lobes, 

 the centre one longest and largest. 



3. LEPTONYX. Skull broad, depressed behind; muzzle short, 



broad ; grinders subcompressed, with a small subcentral co- 

 nical tubercle and a very small posterior one ; the lower jaw 

 narrow behind, without any hinder angle ; fore-feet clawed. 



4. MONACHUS. Skull broad, depressed behind ; muzzle short, 



broad ; orbits large ; grinders small, conical, thick, with a 

 small anterior and posterior lobe ; lower jaw broad, with a 

 distinct posterior angle ; upper cutting teeth transversely 

 notched. 



5. OMMATOPHOCA. Skull broad, depressed behind; muzzle 



very short, broad ; orbits very large ; grinders small, com- 

 pressed, with a central incurved lobe and a small lobe on 

 each side of it ; fore-feet very slightly clawed. 



b. Cutting teeth f ; the first grinder in each jaw single-rooted, 



rest two-rooted ; muzzle bald, and callous between and 

 above the nostrils, and divided by a central groove wrist 

 rather exsertedj fingers subequal ; claws five, large. 

 Phocina. 



6. CALLOCEPHALUS. Muzzle rather narrow ; whiskers waved ; 



palate angularly notched behind; toes gradually shorter; 

 web between the hind-toes hairy ; hair cylindrical ; under- 

 fur thin. 



7. PAGOPHILUS. Muzzle rather produced; whiskers waved; 



palate truncated behind ; toes gradually shorter ; web be- 

 tween hind-toes baldish ; hair dry, flat, close-pressed, with- 

 out any under-fur. 



8. PHOCA. Muzzle broad, short; forehead convex; whiskers 



smooth, simple; palate rather angularly notched behind; 

 ear-hole large ; fingers unequal, the third longest, second 

 and fourth long, the first and fifth shorter, nearly equal. 



B. Grinders with single root (except the two hinder grinders 

 o/Halichcerus). 



c. Ears without any conch j toes simple, of fore-feet exserted, 



of hind-feet large, the inner and outer ones large and long, 

 the three middle ones shorter palm and soles hairy, 

 sometimes chaffy and callous from wear ; muffle hairy to 

 the edge and between the nostrils. 



