1Q) 



FIFTH GENUS. DIODONS. 



The general characters may be stated to be, their having two 

 teeth only in the lower jaw, none in the upper ; forehead 

 depressed ; lower jaw much larger than upper, and convex. 



DIODONS, OR TWO-TEETHED WHALES. 



SEVERAL species are said to belong to this genus ; 

 different, of course, from Hunter's, subsequently 

 discussed. The first we mention is, according to 

 Lesson, the 



DIODON DESMARESTI. 



Delphinus Desmareeti, Risso, 



Risso (Hist. Nat. Nice. t. iii. pi. 2. fig. 3.) de- 

 scribes this cetaceous animal as having a very thick 

 body, especially in the middle, diminishing towards 

 the extremities, and becoming lank in the abdomen. 

 Forehead not prominent, but depressed, terminating 

 iy a long muzzle ; upper jaw short and without 

 teeth ; lower jaw much larger, convex below, and 

 having near its extremity two large conical teeth, 

 three inches long and one broad ; the eye small and 

 oval, with blue iris ; spiracle large, semi-lunar ; 

 pectorals short, dorsal nearly over the vent; tail 



