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



A. INERMES. 



MONACANTHIDA. 



0. 

 DlPLACANTHIDA. 



australis. 

 forcipulosus. 

 nodulosus. 

 mammillatus. 

 vulvulatus. 



Triplacanthida. 



granulosus. 



B. Intermediate forms with small spines on plates 

 of various orders. 



DlPLACANTHIDA. 



chinensis. 

 decipiens. 



C ARMATI. 



MONACANTHIDA. 



0. 

 DlPLACANTHIDA. 



a. Lophial spines alone developed. 

 nodosus. 

 hiulcus. 



/3. Lophial aided by lateral spines. 

 hedemanni. 



y. Lophial and supermarginal spines. 

 lincki. 



I. Inferomarginal spines also. 

 alveolatus. 

 reinhardti. 



e. Ventral spines also. 

 productus. 

 vffinis. 



£. Dorsal spines also. 

 luetkeni, 

 Occident alls, 

 dorsatus. 

 reticulatus. 

 armatus. 



