RELATION OF BIOLOGY TO GEOLOGICAL INVESTIGATION. <>4l 



G \ CTOIDEI. 



KLAS.MOI'.K AM 111 1 



lirai-kish. 



Chima 



Fresh. 



Myliobatidac . . . 

 Cephalopteridffi 



Trygonida- 



Torpedinidse - - - 



Raiida? 



Rhinobatidse. . 

 RhamphobatidiE 



Pristida- 



Sqnatinidae . . . . 

 Heterodonlida- 



Nblidanidse 



Rhinodontidse . 

 Cetorhinidse . . . 



Lanmidse 



Odontaspididaa . 

 Alopeciidse . ... 

 Sphyrnidse 



Trygonida: 



I r\ gonitis. 



Raiida 



Raiida-. 



Prist ida- Priatidse. 



Galeorhioidse 



ScylliidaB 



Gringlymostomatidse . 



C'rossorhinida- 



Spinacidae 



Sevmnida- . — 



Oxynotidae 



Pristiophorida- 



Galeorhiuidae ] Galeorhinida-. 



The following remarks apply only to those families Which have repre- 

 sentatives in more than one of the three kinds of aquatic habitat which 

 arc indicated in the foregoing table. The presence of the name of a 

 family in only oneof the three columns is alone a complete expression of 

 the fact that no representative of it is known in any other habitat than 

 the one thus indicated. It must be remembered, however, that almost 

 any fish whose habitat ranges along the seacoast may occasionally run 

 up into brackish water. Consequently the families enumerated under 

 the head of "brackish" are such only as have representatives habitu- 

 ally living in brackish waters. 



Although the Tetrodontid.e area typically marine family, one species 

 of it is known in South American fresh waters. 



