218 FISHES 



open duct. Moreover, the air bladder is furnished with an 

 unusual amount of blood and undoubtedl)' acts more or 

 less as a lung, for both the gar pike and the bowfin often 

 come to the surface, force out bubbles of air, and take in 

 a fresh supply. 



The sturgeons, which occur in many of the streams and 

 lakes of the northern hemisphere, are the largest of the 

 fresh-water fishes. Those of the lower Columbia River 

 attain a weight of eight hundretl to one thousand pounds. 

 The skeleton, for the greater part, is cartilaginous with 

 no small bones in the flesh. The body has five rows of 

 large bony plates on the outside, but they are not contiguous 

 and do not form a complete covering. The relish, caviar, 

 is made from the roe or egg mas.s of sturgeons. 



The gar pike, also known as the long-nosed gar, or bill- 

 fish, is common in the United States, in lakes and rivers, 

 from Lake Champlain to Texas. It has a long, slemler 

 body accentuated by a long, slender beak, composed of the 

 two jaws, each of whicli is armed with teetli. It approaches 

 the bony fislies in many respects. The body is covered 

 with bony scales forming a complete armor and the skeleton 

 is bony. It attains a length of about five feet. 



Bony fishes. — The members of this order of fishes are 

 distinguished from the preceding types by several charac- 

 ters chief among which is the possession of a bony skeleton. 

 Indeed, this characteristic has given them the distineti^'c 

 appellation of bony fishes. This order furnishes our most 

 important food fishes, such as the lierring, cotl, salmon, 

 mackerel, halibut, etc. 



The mackerel is one of the most important food fishes. 

 It is found from Labrador to North Carolina. They come 

 in great schools, quite regularly in Ma}' and .Tune of each 



