Io8 VERTEBRATE ANIMALS OF THE UNITED STATES 



3. Typhlichthys Girard. Similar to Amblyopsis, except that it 

 has no ventral fins: i species. 



T. suhterraneus Gir. Length 50 mm.; colorless and translucent; 

 rays of dorsal and anal fins 7 or 8 : subterranean streams from Indiana to 

 Alabama; common. 



Order 7. Synentognathi.— Garpike. Soft-rayed fishes with unmodi- 

 fied anterior vertebrae; air bladder without pneumatic duct in the adult; 

 no pyloric caeca; fins without spines; ventral fins abdominal; no adipose 

 fin; lower pharyngeal bones fully united: 4 families of marine fishes, one 

 species of which enters the rivers along the Atlantic coast. 



Family Exocoetidae. — Body very elongate and slender, covered with 

 small scales; lateral line very low, running along the side of the belly; 

 jaws elongated to form a beak, each jaw with a band of sharp teeth; 

 about 50 species of voracious, carnivorous fishes. 



Tylosiirus Cocco. With the characters of the family; no vomerine 

 teeth; tail fin unequally forked: many species, mostly American. 



T. marinus (Walbaum). Garfish; billfish. Length 1,200 mm.; 

 head 2.8; depth 5.5; color greenish; sides silvery, with a narrow silvery 

 lateral stripe; a dark bar on the front of the opercle; rays of dorsal fin 

 15; anal 17; scales 300, 240 before the dorsal fin; body slender, cylin- 

 drical: marine, along the Atlantic coast from Cape Cod to Texas, 

 ascending the rivers and often breeding in fresh water; very common. 



Order 8. Acanthopteri. — The spiny-rayed fishes. Anterior verte- 

 brae unmodified and without Weberian ossicles; ventral fins usually 

 more or less anterior in position, being either thoracic or jugular, and 

 possessing normally i spine and 5 soft rays; anterior rays of dorsal and 

 usually also of anal fins spinous, except in suborders 9 and 10; scales 

 typically ctenoid; margin of mouth formed by the premaxillaries alone; 

 air bladder typically without pneumatic duct in the adult: about 30 

 suborders, mostly of marine fishes, of which 10 suborders (in the 

 United States) include fresh water fishes. 



Key to these Suborders of the Acanthopteri 



ai Ventral fins more or less abdominal in position. 



bi Dorsal fin preceded by 2 or more free spines; sticklebacks, i. Hcmibranchii. 

 hz No free dorsal spines. 



Ci One dorsal fin 2. Salmopercce. 



C2 Two dorsal fins 3. Pcrcesoces. 



a.2 Ventral fins thoracic or jugular in position, 

 bi Fins with spines. 



Ci Body covered uniformly with scales. 



di Spinous dorsal with less than 16 spines. 



