THE VOYAGE OF H.M.S. CHALLENGER. 



TABLE OF TPIE GENERA OF RECENT CHITONS. 



Order POLYPLACOPHORA. 



Section I— CHITONES KEGULAEES. 



Head and tail plates similarly articulated. 



A. — Leptoidea. 



Insertion plates obsolete, or, if present, unslit. 



Leptochiton, Gray. Hemiarthrum, Carp. 



a. DesJiayesiella, Carp. Microplax, Adams and Angas. 



Hanleyia, Gray. 



B. — ISCHNOIDEA. 

 Insertion plates sharp, smooth, fissured ; with eaves. 

 *Nb pores on girdle. 



Trachydermon, Carp. Ischnochiton, Gray. 



a. Trachyradsia, Carp. a. Stenoplax, Carp. 



Callochiton, Gray. b. Stenoradsia, Carp. 



a. Stereochiton, Carp. c. Ischnoplax, Carp. 



Tonicella, Carp. d. Heterozona, Carp. 



Schizoplax, Dall. e. Ischnochiton, Carp., s.s. 



Leptoplax, Carp. f. Ischnoradsia, Shuttleworth. 



Chcetopleura, Shuttleworth. g. Lepidopleurus, Carp. 



a. Maugerella, Carp. h. Lepidoradsia, Carp. 



Spomjiochiton, Carp. Callistochiton, Carp. 



** With girdle-pores. 



Callistoplax, Carp. Ceratozona, Dall. 



Angasia, Carp. Pallochiton, Dall. 



Newcombia, Carp. 



O. — LOPHYROIDEA. 



Insertion plates broad, pectinated, projecting backward. 



Chiton, Linne. Eudoxochiton, Shuttleworth. 



a. Radsia, Gray. Craspedochiton, Shuttleworth. 



Tonicia, Gray. 



a. Fannettia, Dall. 



