56 MAMMALIA. 



jaw ; blow hole twelve inches long in the form of an f, on 

 the anterior extremity of the head; pectorals small and ob- 

 tuse; head divided into cavities or cells communicating with 

 each other, filled with oil which is fluid when the animal is 

 living, when dead takes the concrete form which we deno- 

 minate spermaceti. 



GENUS IV. PHOCCENA, Cuv. 



The Porpoise is of all the Cetacea perhaps best known to 

 us. We shall give the general description in the words of 

 Cuvier. " It has absolutely no hair, not even eyelashes. Its 

 skin is perfectly smooth, and its scarf skin is soft to the touch 

 and easily detached. It has no lips properly so called ; but 

 the skin, always sleek and black, is somewhat strengthened 

 at its union with the gums. The eye is small and situated 

 nearly in the line of the opening of the mouth ; the eyelids 

 are soft and have very little play; their internal surface is 

 moistened with mucus, but there are no puncta lacrymalia, 

 and consequently no tears. The iris is yellowish ; the pupil 

 in form of a v reversed. The opening to the ear is not larger 

 than the point of a pin; that of the blowhole is placed on the 

 top of the head between the eyes, resembling a crescent. No 

 osseous parts in either tail or dorsal fin, but composed almost 

 wholly of fat," 



GFNUS V. BALCENA, Lin. Whales. 



Resembling in size and appearance the Cachalots, but the 

 head not so much enlarged in front; no teeth. The two 

 sides of the upper jaw are armed with transverse laminae 

 called whalebone; lower jaw unarmed. Live upon Worms, 

 Mollusca and Zoophytes. One species (B. Mysticetus) af- 

 fords the whale oil of commerce. 



