CETACEA. 229 



presence in the former of a long narrow beak, almost 

 like that of a bird. Seamen, however, universally 

 apply the term Porpoise to both. Their general 

 form and manners are the same ; the common Por- 

 poise (Phoccena Communis) is the smallest of the 

 Cetacea, rarely exceeding four or five feet. The 

 number of the teeth becomes in these animals a 

 character of little value : the difference in individuals 

 of the same species is often great : they are, however, 

 in the Dolphins very numerous, some kinds having 

 upwards of one hundred and fifty. 



Monodon,* the Narwhal. 



This is a singular and interesting genus, consisting 

 of but a single species (M. Monoceros).-\ It is highly 

 remarkable for the enormous developement of its 

 single tooth into a long straight horn-like tusk, pro- 

 jecting from the head in a line with the body, some- 

 times to the length of nine or ten feet. It is spirally 

 twisted, tapering to a point ; and is composed of the 

 finest ivory. The animal has, strictly, two teeth, but 

 only one is thus prolonged, the other remaining hidden 

 within the jaw ; and in the female both are thus con- 

 cealed. Instances are not wanting, however, in which 

 both teeth have been found nearly of equal length, 

 and that occasionally even in the female. The ani- 

 mal is often called the Sea Unicorn, and all sorts of 

 fabulous powers were formerly ascribed to its horn. 



* Movaj, monoSj single, and oy?, odous, a tooth. 

 *t" Mova;, monos, single, and xigas, keras, a horn. 



