54 BOARD OF AGRICULTURE. 



Order Plectognathi, Guvier. 

 [Soldered Jaws.) 



We next come to fishes that have some peculiarities in the 

 structure of their jaws. The supramaxillarj and intermaxillary 

 bones are united together in a continuous piece, and the palatine 

 arch and cranium are connected by immovable sutures. Hence 

 they are called Plectognathi, (soldered or woven jaws.) The 

 internal skeleton is less perfectly developed than those of the 

 perfect head, (Teleocephali.) The exterior is covered with ganoid 

 plates, granulations, or spines. The branchiae are pectinated and 

 the branchial apertures small. The air bladder has no duct. 



The "balloon fish," "puffers" and " blowers " belong to this 

 order. 



Order LoPHOBRANCHn, Cuvier. 

 [Tufted Gills.) 



All the fishes hitherto examined, have their gills or branchiae 

 fringed like the teeth of a comb, but we now come to a few whose 

 gills are in small round tufts, disposed along the arches in pairs. 

 The branchial apertures small, and on each side of the nape. The 

 jaws are produced into an elongated tubular mouth. The internal 

 skeleton is less perfectly developed than in those with fringed 

 gills. The external skeleton is composed of polygonal plates of 

 a bony, or horny nature, which are joined to each other but per- 

 mit considerable motion in the animal. 



In warm latitudes, there are quite a number of genera of this 

 order, but there are but two in the Eastern Atlantic coast, viz : 

 the " Syngnathus," or pipe fish, a "Hippocampus," or "River 

 Horse," a small fish of the Hudson river. 



This closes up the orders and sub-orders of the first, or upper 

 class of this sytem. Another step down the descending series 

 brings us into the 



Sub-Class Ganoidei, Agassiz. 



Here we find fishes of a mixed oi'ganization, if we may so speak, 

 some of them exhibiting many of the characteristics of the class 

 above them (Teleostei,) the more like the class below, and others 

 intermediate. As revised by Muller, it embraces forms in which 

 the vertebral column and skull are either osseous or cartilaginous. 



