CHONDROPTERYGII. 181 



CHONDROPTERYGII,* CARTILAGINOUS FISHES. 



While in some of the genera of this great sec- 

 tion the general structure is so simple as to make 

 it a subject of doubt whether they are vertebrate 

 animals at all, others seem to manifest an approach 

 to the Reptiles, which sets them above most of the 

 Bony Fishes. It seems, therefore, that these two 

 sub-classes may run parallel with each other, as 

 the two sub-classes of Mammalia do. The skeleton 

 is not, in this division, formed of bone but of carti- 

 lage ; the earthy matter being deposited, not in the 

 form of bony fibres, but in scattered grains. It con- 

 tains two Orders. 



ORDER I. CHAUNOBRANCHIATLt 



THE genera of this first Order manifest an agree- 

 ment with the Bony Fishes in their gills, which have 

 a single wide opening, and are furnished with a gill- 

 cover, but are destitute of rays. 



Acipenser,% the Sturgeon. 



The body of the Sturgeons is much lengthened, 

 and being covered with bony plates in rows, which 



oj, chondros, cartilage, and irrtgvZ,, pteryx, a fin. 

 f* Xetvvos, chaunos, free, and ^a.y^ct t branched, gills. 

 J Its ancient Latin name. 



