POLYPLACOPHORA. 



of the genera of Chitonidcz. 



I 

 I 



d 



a 



1 



K C 



o o 



-r .r 



r 



Liolophurince 



ClIITONIDJE 



ANALYTICAL KEY TO GENERA OF POLYPLACOPHORA. 



a. Fa/re /ac&mp imertion plates, or if present they are wislit 

 (Lepidopleur* 



b. Valves entirely exposed, not immersed, 

 Insertion plates completely absent, 



LEPIDOPLEURUS, p. 2. 



oc. Head valve having an insertion plate, grooved 

 outside hut unslit; valves ii-viii without plates, 

 -mile xpinuloBe HANLEYA, p. 17. 



ccc. Head and tail valves only having unslit insertion 

 plates; girdle thick, sparsely downy, with sut- 

 ural pores HEMIARTHRUM, p. 19. 



