CHAPTER LXI 

 ORDER OF THE DOGFISH 



HALECOMORPHI 



TO naturalists, the Dogfish^ is a creature of much inter- 

 est. Like the i^rong-horned antelope, it is so unique 

 and peculiar that it has been necessary to create for it a 

 grand division of classification which it occupies all alone. 

 The anteloj^e is onl}^ a Family, but this fish is a whole Order. 

 Its other English names are Mudfish, Bowfin, Grindle and 

 Lmnjer; and since Linnaeus christened it Aviia calva, in 

 1766, eleven other naturalists have given it eleven other 

 names in Latin. 



The Dogfish has an air-bladder that is divided into cells, 

 and is a half-developed lung. At intervals it ascends to the 

 surface of the water, gulps down a mouthful of air, just as a 

 turtle does, and descends again. If hindered from rising 

 when the time comes to take in a supply of fresh air, the fish 

 struggles violently, like a mammal about to be drowned; 

 but it can expel air while below the surface. This character 

 indicates that lungs were first developed in fishes from modi- 

 fications of their air-bladders. Other characters establish a 

 distinct relationship with the gar fishes, and place it in the 

 Subclass Ganoidea. The dorsal fin is low, of uniform height 

 throughout, and is about one-half as long as the entire fish. 



1 Am-i'a cal'va. 

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