5 62 



THE OCEAN WORLD. 



the other that the body is, as it were, enclosed in a kind of box or 

 long coffer, which only leaves the external organs of locomotion 

 exposed, namely, the pectoral, dorsal, and caudal fins. In some the 

 body is triangular, in others quadrangular, with or without spines. 



Fig. 369. The Trunk-fish (Ostracion). 



These singular fishes are generally of moderate size, and are found 

 only in the seas of warm climates. 



II. LOPHOBRANCHIA. 



The Lophobranchiate sub- order comprehends but few genera which 

 are pretty numerous in species. Here the gills are formed of small 

 round tufts, and arranged in pairs along the branchial arches a 

 structure quite peculiar, of which we have no examples in any other 

 fishes. These gills are enclosed under a large cover, or operculum, 

 attached on all sides by a membrane, which leaves only a small hole 

 for the escape of water which has served the purposes of respiration. 



Of these little cuirassed fishes the two best-known genera are 

 Syngnathus and Hippocampus. The former, known as pipe-fishes, 

 present a very curious snake-like outline. Their bodies are long, 

 slender, and slightly tapering, covered with plates set lengthwise^ 



