MAMMALIA. 9 



** Teeth, when present, conical: nostrils opening 

 on the crown of the head, acting as blow-holes: 

 whiskers none: mammce near the anus. 



f- Head small : blow-holes united. 



27. DELPHINUS Both jaws with numerous teeth, 

 all simple and equal. 



(1. DELPHINUS.) Snout produced into a beak, broad at its base, 

 rounded at its extremity, and separated from the forehead by a 

 kind of furrow : a dors'al fin. 



(2. PHOCCENA.) Snout short and blunt; not beaked : a dorsal fin. 



(3. DELPHI NAPTERA.) Head blunt; snout not produced: no dorsal 

 fin. 



28. MONODON Head blunt: no true teeth; upper 



jaw with one, rarely two, very long straight tusks pro- 

 jecting forwards in a line with the body : no dorsal fin. 



29. HYPEROODON Snout produced: teeth gene- 

 rally but two in number, placed in front of the lower jaw : 

 palate studded with tubercles : a dorsal fin. 



f**f* Head very large; half or one third of the entire 



length. 



30. PHYSETER Head enormously large, truncated 



in front : upper jaw without whalebone or visible teeth ; 

 teeth in the lower jaw numerous : blow-holes united. 



(1. CATODON.) No dorsal fin. 



(2. PHYSETER.) An elevated dorsal fin. 



31. BALJSNA Head very large: palate furnished 



with whalebone : no teeth : blow-holes separate. 



(I. BAL^ENA.) No dorsal fin. 



(2. BAL^ENOPTERA.) A dorsal fin. 



