232 PISCES. 



There are three subgenera, viz. Hippocampus (the Sea-horse), Soknosto- 

 mus, and Pegasus. 



ORDER VI, 

 PLECTOGNATHI(l). 



We have now passed from the preceding five orders of bony or 

 fibrous fishes, with free and complete jaws, to the sixth, which may 

 be approximated to the Chondropterygii, with which it is allied by 

 the imperfection of the jaws, and the tardy induration of the skele- 

 ton; this skeleton, however, is fibrous, and its whole structure is that 

 of ordinary fishes. The most distinguishing character of the order 

 consists in the maxillary bone being soldered to the side of the in- 

 termaxillary, which alone constitutes the jaw, and in the mode in 

 which the palatine arch is connected with the cranium, which, being 

 by a suture, consequently renders it immovable. Besides this, the 

 opercula and rays are concealed under a thick skin, through which 

 only a small branchial fissure is visible. Of ribs, nothing is to be 

 found but very small vestiges. There are no true ventrals. 



This order comprises two very natural families, characterized by 

 their mode of dentition. 



FAMILY I. 



GYMNODONTES(2). 



The Gymnodontes have jaws, which, instead of teeth, are fur- 

 nished with an ivory substance, internally divided into laminae, whose 

 ensemble resembles the beak of a Parrot, and which in fact consists 

 of true teeth united, that succeed each other as fast as they are de- 

 stroyed by trituration. The opercula are small, and there are five 

 rays on each side, all of which are but imperfectly seen. They live 

 on Crustacea and fucus, their flesh is mucous, and that of several 

 species is considered poisonous, at least in certain seasons. 



(1) Cheeks united by suture. (2) Naked teeth. 



