PISCES 



241 



Fig. 118. Short-nosed sturgeon. (Nichols 

 and Breder. N. Y. Zool. Soc.) 



many tactile and gustatory end organs. A relative of the American 

 spoon-bill lives in the waters of China. 



The sturgeon {Acipenser) (Figure 118) has its rostrum prolonged 

 into a snout with a transverse row of barbels hanging from the 

 ventral surface. The scales 

 are large and arranged in five 

 longitudinal rows, and have 

 keels. The sturgeons are 

 found in the Great Lakes, 

 and in the Black and Caspian 



seas. Caviar, is made from the eggs of sturgeons, and their flesh 

 is also eaten. They reach a size of thirty-two hundred pounds. 



Order 3. Holostei. — Holostei are between the Elasmobranchs 

 and the Teleosts, and include Amia and Lepidosteus. They have 

 the cartilaginous and bony skeleton, ganoid scales, swim bladder 

 and pyloric appendages of the teleosts; and the conus arteriosus and 

 spiral valve of the elasmobranchs. The tail is diphycercal. (See p. 



The gar pikes {Lepidosteus) are fresh water fishes, ranging from 

 five to ten feet (Alligator gar), and found in North and Central 

 America. They have long slender bony snouts with sharp teeth, 

 and kill many other fishes. The air bladder serves as a lung when 

 the animal comes to the surface to gulp in a fresh supply of air. 

 (Figure 119.) 



Fig. 119. Long-nosed gar. (Courtesy of N. Y. Zool. Soc.) 



The bow fin, Amia calva, called the " mudfish " or " fresh water 

 dog fish," resembles the true bony fishes. It has, however, a 

 continuous dorsal fin, heavy ganoin covered scales and a tail modi- 

 fied from the heterocercal to a shape almost homocercal. The air 



