MUSEUM 01'' L'OMrAllATIVE ZOOLOGY. 165 



EXPLANATION OF THE PLATES. 



Tiie figures of shells were drawn by Mr. Arthur F. Gray ; those of genitalia and lingual deutiiiou, 



by W. G. Cinuey. 



PLATE I. 



Mesodon Cliilowecnsis : linyual dentition. 



" " genitalia. 



Patula Bryanti. 

 Ilelicodiscus fimbriatus. 

 Triodo[)sis Levettei. 

 Zonitcs petrophilus. 

 Wlieatleyi. 

 Vitrinozonites latissimus : lingual dentition. 

 Arionta intcrcisa : Ungual dentition. 

 Triodopsis Copei. 



Arionta Mormonum, var. circumcarinata. 

 Zonites UpsonL 



PLATE IL 



Fig. A. Zonites placentula. 



" B. " niacilentus. 



" C. " cuspidatus. 



" D. " Andrews!. 



" E. " Lawi. 



" F. " niultidcntatus. 



" G. " significans. 



" H. " Rugeli: slicll. 



" L " " dentition. 



" J. " subplanus : dentition. 



" K. Mesodon Chiloweensis. 



" L. " Andrcwsi. 



" M. :\Iacrocyclis HempliiUi. 



" N. Micropliysa Stearnsi : dentition. 



•' 0. " " jaw. 



