64 PROF. F. J. BELL ON THE [Feb. 19, 



A. INERMES. 



MoNACANTHIDA. 



0. 

 DiPLACANTHlDA. 



australis. 

 forcipulosus. 

 nodulosus. 

 mumnnllatiis. 

 valvulatus. 



Triplacanthida. 



graitulosus. 



B. Intermediate forms with small spines on plates 

 of various orders. 



DiPLACANTHlDA. 



chinensis. 

 decipiens. 



C. AEMA.TI. 



MoNACANTHIDA. 



0. 

 DiPLACANTHlDA. 



a. Lophial spines alone developed. 

 nodosus. 

 hiulcits. 



/3. Lophial aided by lateral spines. 

 hedemanni. 



y. Lophial and superomarginal spines. 

 lincki. 



I. Inferomarginal spines also. 

 alveola tus. 

 reinhardti. 



e. Ventral spines also. 

 productus. 

 ajjinis. 



i,. Dorsal spines also. 

 luetkeni. 

 occidentalis. 

 dorsatus. 

 reticidatus. 

 armatus. 



