PISCES, TRUE FISH 447 



with the upper lobe quite extended and slender. There are no teeth 

 in the mouth. Acipenser fulvescens is the Mississippi Valley form, 

 and, though it was once abundant, it can now be found only occa- 

 sionally. Both families of this order furnish both flesh and roe 

 (caviar) as food for man. 



Order Holostei. — Gar pikes and Bowfins. This is another ganoid 

 type but with a more complete bony skeleton. In most of the repre- 

 sentatives of the order, the scales are of the enamellike ganoid 

 variety, but in a few they are cycloid and imbricated. 



Family Amiidae. — Bowfin or Fresh-water Dogfish. In Amia calva, 

 the only species in existence, we find the cycloid scales and another 

 form capable of accessory respiration by means of swim bladder. 

 They inhabit the fresh-water lakes and sluggish streams as far 

 southwest as east Texas. 



Family Lepisosteidae. — Gar pikes (garfishes). The long-nosed 

 gar and alligator gar are the most common southwestern forms, 

 while the long-nosed and short-nosed are the common species of 

 the Middle West. These are covered with a strong armor of 

 rhombic, enamellike, ganoid scales. The pelvic fin is abdominal and 

 the dorsal fin is far to the posterior. The snout is conspicuously 

 extended, and the tail is heteroeercal. 



Order Teleostei. — True Bony Fishes. A group which includes the 

 majority of existing fishes. It is thought to have descended from 

 the ganoid type. Some are soft-rayed fishes with open connection 

 between swim bladder and alimentary canal (Physostomi), and 

 others are spiny-rayed fishes with no air duct from swim bladder 

 (Pkysoclisti). Their skeletons are highly ossified. They have cycloid, 

 ctenoid, or no scales and their type of tail is usually homocercal. 



Suborder Isospondyli. — Tarpon, Herring, Salmon, etc. 

 Family Elopidae. — Ten-pounders. Found in warm marine waters. 

 Flops saurus is the typical representative. 



Family Megalopidae. — Tarpons. This is a very active game type 

 of fish with large scales and an extended filament from the dorsal 

 fin. It is very abundant throughout the Gulf of Mexico and is a 

 famous game fish all along the Texas-Louisiana coast. 



Family Hiodontidae. — Mooneyes. Fish of this family have greatly 

 compressed bodies which are covered with large, silvery, cycloid 



