454 COLLEGE ZOOLOGY 



for stirring up the mud and its barbels for locating snails, cray- 

 fishes, and insect larvae. Sturgeon flesh is a valued article of 

 food, the eggs are made into caviar, and the air-bladders furnish 

 isinglass. 



Orders. Holostei. - - Most of the HOLOSTEI are extinct; 

 only two of the eight families have living representatives, 

 namely the LEPISOSTEID^E or garpikes, and the AMUD^E or bow- 

 fins. These fishes are called bony ganoids, since the skeleton 

 is bony and the scales are often ganoid. In some the scales are 

 cycloid (Fig. 371). The tail is diphycercal or homocercal, with 

 a tendency toward the heterocercal type, and the ventral fins 



FIG. 383. The alligator-gar, Lepisosteus tristaschus. (From Jordan 



and Evermann.) 



are abdominal. The living species of garpikes and bowfins are 

 known only from America. 



The garpikes belong to the genus Lepisosteus. There are 

 three common species, the long-nosed garpike, .the short-nosed 

 gar, and the alligator gar (Fig. 383). The long-nosed gar, Lepi- 

 sosteus osseus, is common in the lakes and rivers of the United 

 States. It is about four feet long. The body is slender with an 

 extended beak, at the end of which are the nostrils. Its heavy 

 ganoid scales effectively protect it from every other living crea- 

 ture in the water. Garpikes are voracious, devouring minnows, 

 young fish, and other aquatic animals, and where they occur in 

 large numbers are very harmful to the fishing industry. 



Amia (Amiatus) calva, the mudfish, fresh- water dogfish, or 

 bowfin (Fig. 384), is the only existing representative of the family 

 AMIID^E. It inhabits the sluggish waters of the Great Lakes region 



