PISCES. 95 



so styledf and that of the Chondropterygii, otherwise called 

 Cartilaginous Fishes. 



The general character of the latter consists in the absence 

 of the bones of the upper jaw, whose place is supplied by those 

 of the palate ; their whole structure also exhibits evident ana- 

 logies which we will describe : it is divided into three orders. 



The Cyclostomi, whose jaws are soldered in an immova- 

 ble ring, with branchial openings. 



The Selachii, which have the branchiae of the Cyclostomi 

 but not their jaws. 



The Sturiones, whose branchial opening is the usual fis- 

 sure furnished with an operculum. 



The other series, or that of the Ordinary Fishes, pre- 

 sents a primary division in those where the maxillary bone 

 and the palatine arch are fixed to the cranium : they consti- 

 tute an order which I call that of the Plectognathi, and 

 are divided into two families: the Gymnodontes and the 



SCLERODERMI. 



I next find fishes with perfect jaws, but whose branchiae, 

 instead of being pectiniform, resemble a series of small tufts ; 

 they also constitute an order which I call Lophobranchii, 

 that comprises but a single family. 



There then remains an immense number of fishes to which 

 no other characters can be applied than those of the external 

 organs of motion. After much long, and laborious research, I 

 have found that the least objectionable of these characters is 

 the one employed by Ray and Artedi, drawn from the nature 

 of the first rays of the dorsal and anal fin. Thus the ordinary 

 fishes are divided into Malacopterygii, where all the rays 

 are soft, with the occasional exception of the first of the dor- 

 sal or of the pectorals, and into Acanthopterygii, in which 

 the first portion of the dorsal, or of the first dorsal where 

 there are two, is always supported by spinous rays, and where 

 some of the same are always found in the anal fin, and at least 

 one in each of the ventrals. 



The first may be divided by a reference to the position of 

 their ventral fins, which are sometimes situated behind the 



