258 



CLASSIFICATION OF VERl^EBRATES. 



GASTEROSTEID^E ; body naked or with bony plates ; dorsal with spines ; 

 teeth sharp, in jaws alone ; anal with one spine ; fresh and brackish 

 water. Gastcrosteus, Apeltes, sticklebacks. CENTRISCIDA:, two dorsals, the 

 first spiny; marine. FISTULARIID^E, bony plates are present; the dorsal is 

 without spines ; snout produced into a tube ; the species are marine. Fistu- 

 laria has persisted since the eocene. The extinct DERCETID^E (Belonor- 

 hynchus, Saurorhamphus from the cretaceous) show relations towards 

 Belone. 



ORDER V. LOPHOBRANCHII. 



Teleosts with hemibranch ances- 

 try ; body armored with segmented 

 bony armor ; snout elongate ; tooth- 

 less ; operculum a single plate ; gills 

 composed of small rounded tufts ; 

 air-bladder simple, physoclistous ; 

 shoulder girdle connected with the 

 cranium. 



SOLENOSTOMID^:, large gill openings ; 

 two dorsals and ventral fins. Solenorhyn- 

 chus, eocene ; Solenostoma, eocene of Europe 

 and Pacific Ocean to-day. The females carry 

 the eggs and young in a brood pouch formed 

 by the ventral fins and the abdominal or cau- 

 dal surface. SYGNATHID.E, appears in the 

 middle tertiary; gill opening very small; a 

 single dorsal fin and the ventrals absent. 

 Sygnathits and Siphostoma, pipe-fish, have 

 a caudal fin. In Hippocampus, sea-horses, 

 the tail is prehensile and the caudal ab- 

 sent. 



FIG. 259. Sea-horse, Hippo- 

 campus heptagonus, after Goode. 



ORDER VI. ACANTHOPTERYGII (ACANTHOPTERI). 



Gills laminate ; ctenoid or cycloid scales ; premaxillaries 

 forming the border of the mouth ; shoulder girdle connected to 

 the cranium by a (usually forked) post-temporal ; ventrals gen- 

 erally far forward, usually attached to the shoulder girdle by 

 means of the pelvis ; the anterior rays of pectorals, ventrals, 

 dorsal or anal fins, usually osseous spines. Here belong the 

 great majority of marine teleosts. Judging from vertebral char- 

 acters and the suspension of the pectoral girdle, they have prob- 



