488 



EDWIN S. GOODRICH. 



Ryder (32), the only author who seems freely to have 

 speculated on this subject, believed all the dermal rays to be 

 homologous with and derived from the " horny " type found 

 in Elasmobranchs. Concerning the origin of these cerato- 

 trichia little can be said. That they should have been 



Fig. 4. — Diagrammatic figure of a section t,ln-o\igli tlic dorsal fin of 

 a Telensleaii fish. For tlie lettering sec p. 517. 



derived from the basal plates of the denticles, as suggested 

 by Klaatsch (21), if I understand him rightly, seems most 

 unlikely. Neither in their development nor in their structure 

 have the two anything in common, beyond the fact that they 

 are both produced in tlie mcsobhist. Tlie rays develop in the 

 fins long before the denticles themselves put in an nppearauce. 



