FISHES. 375 



III. STURIONES. Branchiae opening as usual in a cleft pro. 

 tected by an operculum. 



The SECOND SERIES consists of the Osseous Fishes, or fishes 

 with fibrous and hard bones, and these are subdivided into 

 orders as follows : 



IV. PLECTOGNATHI. Maxillary bone and palatine arch 

 fixed to the cranium. 



V. LOPHOBRANCHII. Fishes with complete jaws, but with 

 the branchiae in small tufts. 



For the subdivision of the remainder of this numerous class 

 M. Cuvier, after much investigation, found no characters bet- 

 ter suited than those employed by Ray and Artedi, derived 

 from the nature of the rays of the dorsal and anal fins. 

 This great portion of the class he therefore divides into two 

 groups, viz. 1. MALACOPTERYGII, in which all the rays are 

 soft, except sometimes the first of the dorsal or pectoral fins ; 

 and 2. ACANTHOPTERYGII, which have always the first por- 

 tion of the dorsal fin, or the first dorsal fin itself where there 

 are two, supported by rigid or spinous rays, and where also the 

 anal fin possesses some rays of the same nature, and the ventrals 

 at least one each. To make these two groups orders would 

 naturally occur as the most proper division ; but both include 

 so many genera, and such a multitude of otherwise disjoined 

 species, that Cuvier subdivides the first, or the Malacopterygii, 

 into three orders, according to the position of their ventral fins. 

 The necessity of a double term for these orders cannot in this 

 view be avoided. 



VI. MALACOPTERYGII ABDOMINALES. Ventral fins on the 

 hinder part of the abdomen. 



VII. MALACOPTERYGII SUBRACHIATI. Ventral fins under 

 the pectorals, on the throat. 



VIII. MALACOPTERYGII APODES. Destitute of ventral fins. 



This method of subdivision M. Cuvier having found imprac- 

 ticable with the numerous group of Acanthopterygious fishes, 

 he divides them into natural families, to which the charac- 

 ters of the subordinate groups afford considerable facilities; 



lies of his Chondropterygii with fixed branchiae. We have preferred, with Latreille, 

 the arrangement which makes them separate orders. But in any view they are natural 

 families with strongly marked characters. 



