MAMMALIA. 7 



base : front-Ucih in the lower-jaw S: canhu-;eeth nono: 

 chin of the male bearded. 



19. Ov is. Horns hollow, wrinkled, turned backwards and 

 spirally twisted inwards : front-teeth in the lower-jaw 

 8 : canine-teeth none. 



SO. Bos. Warns hollow, smooth, turned outwards and 

 forwards, crescent-shaped: front-teeth in the lower- 

 jaw 8 : canine-teeih none. 



ORDER V. BELLU/E. 

 Front-teeth obtuse, truncate : feet hoofed.. 



21. Equus. Front-teeth m the upper-jaw 6,, parallel ; 

 in the lower-jaw 6, rather projecting: tusks one each 

 side in each jaw, remote from the rest: hoofs un-r 

 divided. 



22. Sus. Front-teeth in the upper-jaw 4, converging ; in 

 the lower 6, projecting: tusks in the upper-jaw 2, 

 rather short; in the lower 2, long, and at length 

 exserted : hoofs cloven. 



ORDER VI. CETE. 



With spiracles, or breathing holes, on the forepart of the head: 

 feet none: pectoral fins without claws: tail placed hori- 

 zontally. 



23. Mono don. Head furnished with one or two long 

 spirally twisted teeth, projecting straight forwards, 

 like horns, through the upper lip: spiracle on the 

 head. 



24. Bal,ena, Teeth none, instead of which are horny 

 lamina? in the upper-jaw : spiracle with a double ori- 

 fice, on the top of the head. 



55. Physeter. Teeth visible in the low T er-jaw only: 



spiracle on the head or snout. 

 26. Delphinus. Teeth visible in each jaw: spiracle or 



the head, 



