MUSEUM 01' COMrAKATIVE 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. Einuey. 



PLATE L 



Fig. A. Mesodon Cliiloweensis : lingual dentition. 



" B. " " genitalia. 



'• C. Patula Bryanti. 



" D. Helicodiscus fimbriatus. 



" E. Triodopsis Levettei. 



" F. Zonites petrophilus. 



" G. " Wheatleyi. 



" H. Vitrinozonites latissimus : lingual dentition. 



" L Arionta intercisa : lingual dentition. 



" J. Triodopsis Copei. 



" K. Ari(jnta Mormonum, var. circumcarinata. 



" L. Zonites UpsonL 



PLATE IL 



Fig. A. Zonites plaeentula. 



" B. " macilentus. 



" C. *' cuspidatus. 



" D. " Andrewsi. 



" E. " Lawi. 



" F. " niultidcntatus. 



*' G. " significans. 



" H. " Rugeli: sliell. 



'■ I- " " dentition. 



" J. " subplanus : dentition. 



" K. Mesodon Cliiloweensis. 



" L. " Andrewsi. 



" M. IMacrocyclis Hemphilli. 



" N. Micropliysa Stearnsi : dentition. 



'' O. " " jaw. 



