180 VERTEBRATA. PISCES. 



spines ; their tail is exceedingly short but high, 

 and united to a high and pointed dorsal and anal, 

 whence they derive a singularly grotesque appear- 

 ance. They are noted for their luminous radiance 

 at night ; and as they are of large size, four feet 

 in diameter, and almost globular, they are said to 

 be visible far down in the depths of ocean, and to 

 look like great globes of red-hot iron. They occa- 

 sionally appear to sleep at the surface. 



FAM. II. SCLERODERMATA.f 



These are distinguished by a conical snout, pro- 

 longed from the eyes, and ending in a small mouth, 

 armed with a few distinct teeth in each jaw. The 

 skin is usually rough, or invested with bony plates. 



Ostracion. J 



The covering of this genus is exceedingly hard, 

 composed of numerous pieces joined with the great- 

 est regularity, and often with a mathematical pre- 

 cision, in hexagonal plates. So inflexibly are these 

 soldered together, that the only moveable parts are 

 the tail, fins, and mouth, so that they may not un- 

 aptly be compared to the Tortoises. They are gene- 

 rally somewhat triangular in vertical transverse sec- 

 tion. Some species, as 0. Cornutus, are singularly 

 armed with projecting spines on the head and be- 

 neath the tail. They are chiefly found in the tro- 

 pical seas. 



* 2*A?off, skleros, hard, and ^'I^K, derma, skin. 

 *f ''O<rrga,xov, ostrakon, a shell. 



