164 MAMMALIA. CETACEA. 



M. monoceros, Lin. Body ovoid; head equal to a fourth of the 

 length of the animal ; left tusk only developed, furrowed in a 

 spiral form, half the length of the body ; colour grayish in the 

 young, marbled or blackish in the old. Length 20 to 30 feet. 

 Northern Ocean. Shaw, ii. pi. 225. 



The Narwhal is of an ovoid form, and from twenty to thirty feet long. Its upper 

 jaw, more advanced than the under, is covered by a thick lip, and from each side of 

 this jaw projects a long narrow tusk terminating in a sharp point. This tusk, pre- 

 served in the cabinets of the curious, was long conceived to be the horn of the fabulous 

 unicorn. 1 1 was afterwards conjectured to be placed upon the forehead of the Narwhal ; 

 till later and more correct observation discovered it to be one of two tusks proceeding 

 from the upper jaw of the animal. This tusk or tooth is twisted spirally through 

 its entire length, and is harder than ivory. With this powerful instrument he at- 

 tacks his prey, and often destroys the whale. 



2d Division. Head very large. 

 Gen. 151. PHYSETEK, Lin. Cuv. Physalus, Lacep. 



Inferior teeth 18 to 23 on each side of the jaw ; upper jaw broad, 

 elevated, without teeth, or with these short and concealed in 

 the gum ; lower jaw elongated, narrow, corresponding to a 

 furrow of the upper, and armed with thick and conical teeth, 

 entering into corresponding cavities in the upper jaw ; spi- 

 racular orifices united at the upper part of the snout ; a dorsal 

 fin in some species, a simple eminence in others; cartilaginous 

 cavities in the superior region of the head filled with oily 

 matter. 



Sub-Gen. 1. CATODON, Lacep. No dorsal Jin. 



P. macrocephalus, Desm. Great-headed Cachalot. Lower teeth 20 

 to 23 on each side, recurved and pointed at the extremity ; small 

 conical teeth concealed in the upper gums ; tail narrow and coni- 

 cal ; a longitudinal eminence on the back above the anus ; upper 

 part of the body blackish or slate-blue, a little spotted with white ; 

 belly whitish. Length 45 to 60 feet. Northern Seas Shaw, ii. 

 228. 

 The usual length of the Macrocephalus is upwards of seventy feet, and its head 



is the largest of any known animal. It is more than a third the length of the body, 



truncated in front and almost cubical. The spermaceti, for which it is chiefly killed, 



is found in membranous cells. 



Sub-Gen. 2. PHYSETER, Lacep. With a dorsal Jin. 



P. microps, Lacep. Lower teeth 21 on each side, arched, the points 

 directed backwards ; dorsal fin large, erect, and pointed ; pecto- 

 ral fins large ; eyes very small. Length 70 to 80 feet. North- 

 ern Seas. Mam. 525. 

 An individual of this species, fifty-four feet long, was stranded at Cramond Island, 



in the Firth of Forth, 22d December 17G9. 



P. sulcatus, Desm. Teeth of the lower jaw pointed and straight, 

 with inclined furrows on each side of the jaw ; dorsal fin conical, 

 situated above the pectorals. Seas of Japan Mam. 526. 



Gen. 152. BAL^NA, Lin. Cuv. Desm. Bal&noptera, Lacep 

 No teeth ; upper jaw keel-formed, furnished on each side with 



