CH0NDR0PTERYGI1. 629 



roe of the female, weighing nearly one-third of the entire fish. 

 This caviar is principally used, however, in Turkey, Russia, 

 Germany, and Italy. It constitutes almost the entire food of 

 the Greeks during their long fasts, and affords a great revenue 

 to Russia. The fish is valuable moreover not merely for its 

 eggs; the flesh is white, fat, and a good deal like veal, and is 

 very nutritious, wholesome, and agreeable to the taste. 



Nothing is known relative to the habits of that singular 

 fish, which alone at present constitutes the genus Spatu- 

 la ria of Shaw, Polyodon, Lacep., and its external cha- 

 racters are sufficiently detailed in the text. It is, however, 

 impossible to convey by words even a notion of this, as well 

 as many other oddly-formed species of this class. The 

 subjoined figure is therefore inserted in aid of the verbal 

 description already given. It does not in general much 

 exceed a foot in length, and is of a uniform greyish colour. 



The Chondropterygians with fixed gills. 



We proceed to the chondropterygian fish with fixed gills, 

 the first family of which includes the large genus Squalus, 

 of Lin., the Sharks, now divided into several subgenera, with 

 reference to the air-holes on the neck, the single post-anal 

 fin, the disposition of the head, muzzle, teeth, &c. ; and the 

 Rays. 



The mode of generation in these fish, singular for the 

 class, though common in the other great divisions of the 

 animal kingdom, has been already alluded to in the text. 

 The several species are ovoviviparous, that is, the eggs are 

 hatched in the matrix or oviduct of the mother ; but it some- 

 times happens, that these eggs are expelled before the embryo 

 has quitted them, which it seems, however, does not destroy 

 the young, which in due time will quit its singular covering. 



