242 



PISCES 



bladder is used as a lung. The male guards the nest and later takes 

 care of the young for a short time. The embryonic development is 

 less like that of a teleost than of an amphibian. (Figure 120.) 



Order 4. Teleostei. (Gr. — complete, — a bone.) — The teleosts 

 include most of our common food fishes. The skeleton is ossified. 

 Except for one genus, the spiral valve is absent. The stomach has 



Fig. 120. Bowfin, Jmia caha. (From L. A. Fuertes. Courtesy of Slingerland- 



Comstock Publishing Co.) 



pyloric appendages (120 in the cod). The scales are cycloid or 

 ctenoid. The gills are comblike and an operculum is always present. 

 The swim bladder is usually present though its duct is not always 

 open. The eyes are large and lidless. The optic nerves of Teleostei 

 cross each other, without interlacing. 



^ The A kaj'inp tarp n {Elopidae), (Figure 121) called the " silver 

 king," is much sought by fishermen as it is a gamey fighter. Its 



Fig. 121. Tarpon. (From Goode. U. S. B. F.) 



large silvery scales furnish ganoin for the manufacture of ornaments. 



The salmon {^Salmonidae) is a marine fish spawning in fresh 

 water at the age of four or five years. Its long migration to an- 

 cestral spawning grounds has puzzled and thrilled scientists for 

 many years. (See page 263.) 



The white fish lives in deep water in the winter and migrates to 



