CHAP. XX.]' FISHES. 457 



Family 89.— SYNGNATHID^. (15 Genera, 112 Species.) 



" Marine Lophobranchii, witli very small gill opening and one 

 soft dorsal fin." 



DiSTKiBUTiON. — All the tropical and temperate seas. Some 

 species of Syngnathus, Doryichthys, and Gtdonotus enter fresh 

 water, and a few live in it exclusively. Siphonostoma, Syngna- 

 thtcs, NeropMs, and Hippocampus are British genera. The 

 Hippocampina (5 genera, 25 sp.), or Sea-horses, are peculiar to 

 the Indian and Pacific Oceans, except three or four species of 

 Hi'ppocampus in the Atlantic and Mediterranean. 



Order VL—PLEGTOGNATEI. 



"Fishes covered with rough scales or shields, having a 

 narrow mouth, and soft posterior dorsal fin." 



Family 90.— SCLEEODERMI. (7 Genera, 95 Species.) 



" Marine Plectognathi, with toothed jaws." 



DiSTKiBUTlON. — Temperate and Tropical seas, but much more 

 abundant in the Tropics. 



Family 91.— GYMNODONTES. (10 Genera, 82 Species.) 



" Marine or fresh-water Plectognathi, with jaws modified into 

 a beak." 



Distribution. — Temperate and tropical regions. 



Some species of Tetrodon are found in the rivers of Tropical 

 America, Africa, and Asia. Species of Tetrodon and Ortha- 

 goriscus have been found on the British coasts. 



