Selection of Experimental Fishes 



THERE IS obviously a considerable morphological 

 and physiological difference between the primitive 

 and recent fishes, or one might say there is a phyloge- 

 netic basis for selecting an experimental fish. The 

 bony fishes, class Osteichthyes, may be divided into 

 the fleshy-finned fishes and the rayed-fin forms. The 

 first group is for the most part extinct and of no inter- 

 est here. The rayed-fin forms may be divided into the 

 three groups: Chondrostei, Holostei, and Teleostei. 

 The first group is represented in our fauna by the pad- 

 dle fish ( Polyodon spatula ) and sturgeons ( Acipenser 

 spp. ) and the second by gar pikes ( Lepisosteus spp. ) 

 and the bowfin {Amia calva). Both of these groups 

 are poorly represented in present day fauna, and 

 forms available are too large for most experimental 

 work. 



The group Teleostei includes the great majority of 

 our present day fishes, but even within this group 



