32 VERTEBRATE ANIMALS OF THE UNITED STATES 



Key to the Families of Holostei 



ai Body covered with ganoid scales i. LepisosteidcB. 



SL2 Body covered with cycloid scales 2. Amiidce. 



Family i. Lepisosteidae. — The garpikes. Body elongate and 

 subcylindrical, with rhombic ganoid scales; jaws elongate, forming 

 a long slender snout, the upper jaw of which is composed mostly of 

 the premaxillaries; opercle supporting an accessory gill; branchiostegals 

 3; spiracles absent; spiral valve rudimentary; rays of both dorsal and 

 anal fins 8 : i genus. 



Lepisosteus Lacepede {Lepidosteus Agassiz). With the characters 

 of the family: about 4 species in the fresh waters of North America, 

 one of which (L. tropicus Gill) is in Central America; flesh usually 

 not used for food, except in the southern States. 



Key to the United States Species of Lepisosteus 



ai Snout more than twice as long as rest of head L. osseus. 



0,2 Snout about as long as rest of head. 



bi A single row of large teeth on each side of upper jaw L. platostomus. 



b2 Two rows of large teeth on each side of upper jaw L. tristcechus. 



L. osseus (L.). Common garpike. Length 1,300 mm.; head 3; 

 depth 10 to 13; color olivaceous, silvery below; hinder parts with 

 black spots; very young animals with a black lateral band; scales 

 in lateral line about 62: Great Lakes and Mississippi Valley to the 

 Rio Grande; Atlantic and Gulf slope from Vermont southwards; 

 in rivers and lakes, sometimes entering the sea; common. 



L. platostomus Rafinesque. Short-nosed gar. Length 900 mm.; 

 head 3 to 3.9; depth 8 to 10; color olivaceous, but darker thanL. osseus; 

 scales in lateral line 56: Great Lakes and Mississippi Valley to Rio 

 Grande; common; more so southwards. 



L. iristceclius (Block and Schneider). Alligator gar (Fig. 15). 

 Length up to 6,000 mm.; head 3.7; depth 8; color greenish, paler below; 

 scales in lateral line 60: southern States, north to the Ohio and lUinois 

 Rivers. 



Family 2. Amiidae. — The bowfins. Body fusiform, compressed, 

 with cycloid, imbricated scales; head subconical, covered with a hard 

 bony helmet; snout short; branchiostegals 10 or 12; no opercular 

 gill or pseudobranchiae; dorsal fin very long; tail convex behind, some- 

 what heterocercal ; lateral line present : i genus. 



Amia L. (Amiatus Rafinesque). With the characters of the 

 family: i species. 



