HOLOSTEI 503 



ossified, opisthocoelous knd. fused with the neural arches. The 

 metapterygoid bones have a secondary articulation ^^■ith the 

 skuU.^ Maxillae segmented into numerous pieces. Jugular plates 

 absent. Branchiostegal rays reduced to three on each side. Teeth 

 numerous, slender, and of unequal size. In the larger teeth the 

 dentine is intricately folded. Pyloric caeca branched and com- 

 pacted together into a gland-like mass. Air-bladder cellular, but 

 its blood is not derived from a posterior aortic arch. 



The only known genus is Lepidosteus, the existing species of 

 which frequent the fresh waters of North America.^ The common 

 or Long-nosed Gar-Pike (Z. osseus), remarkable for its long and 

 slender beak, is generally abundant in the rivers and lakes of the 

 United States from Vermont to the Eio Grande, and it may reach 



Fig. 299. — Sliort-nosed Gar Pike {Lepidosteus platystomus.) x i. (From BasMord 

 Deau, after Goode. ) 



a length of five feet. The " Short-nosed Gar " (X. platystomus, 

 Gutither) has a much shorter and broader beak, and a similar dis- 

 tribution (Pig. 299). The "Great" or "Alligator Gar" (Z. 

 viridis, Gtinther) has a more southerly habitat, frequenting the 

 rivers of the Southern States, IsTorthern Mexico, and Cuba. It 

 is by far the largest species, sometimes reaching a length of 8 to 

 10 feet. 



Lepidosteus is a voracious Fish, preying upon smaller Pishes, 

 and, except in the breeding season, it frequents the deeper parts 

 of the rivers or lakes. The Pish is constantly in the habit of 

 rising to the surface and emitting bubbles of gas, either through 

 the mouth or by the branchial clefts, and it is probable that this 

 gas is air which has been previously swallowed at the surface 

 and passed into the air-bladder. About May Lepidosteus resorts 

 in large numbers to. shallower water, where the temperature is 



^ It is possible that a similar articulation is present in Lepidotus (Smitli Wood- 

 ward, Brit. Mus. Cat. Foss. Fishes, iii. p. 79). 

 ^ Jordan and Evermann, op. cit. p. 108, et. seq. 



