THE FISHES 171 



Often this organ is altogether wanting, as in the common 

 mackerel. About twelve thousand kinds of bony fishes ara 

 known. The species swarm in every sea, lake, or river 

 throughout the earth, and some form or another among 

 them is familiar to every boy in the land. These fishes art. 

 divided into about two hundred families, and these may be 

 arranged in fifteen to twenty orders. As these are mostly 

 distinguished by features of the skeleton, we need not name 

 them here. In Jordan and Evermann's Fishes of North 

 and Middle America, as well as in various other books, the 

 student of fishes can find the characters by which orders 

 may be distinguished. 



161. Sturgeons and garpikes (Ganoidei). "While the great 

 majority of the typical fishes possess a bony skeleton, there 

 are a few quaint types the ganoid fishes showing ancient 

 traits. In some of these, as the sturgeon, the skeleton is 

 cartilaginous. In the garpike and bowfin it is long, as in 

 the teleosts. Most of this group are now extinct. At 

 present in this country the ganoids are represented by sev- 

 eral species, the best known being the sturgeons. These in- 

 habit the Great Lakes, the Mississippi, and its tributaries ; 

 while other species ascend tli3 rivers to spawn. These are 

 the largest fishes found in fresh water, attaining a length 

 of ten or twelve feet, and a weight of five hundred pounds. 

 Their food consists of small plants and animals, which they 

 suck in through their tube-like mouth. The garpikes live 

 in the larger lakes and rivers throughout the East and 

 Mississippi Valley. Their bodies, from three to ten feet in 

 length, according to the species, are covered with compara- 

 tively large regularly arranged square scales, and the upper 

 jaw is elongated to form a kind of beak, abundantly sup- 

 plied with teeth. They are carnivorous, voracious fishes, 

 working great havoc among the more defenseless food- 

 fishes. Equally destructive is the voracious bowfin (Amia), 

 a fish useless as food, but of very great interest from its 

 relation to extinct forms. 



