MUSEUM OF COMPARATIVE ZOOLOGY. 165 
EXPLANATION OF THE PLATES. 
The figures of shells were drawn by Mr. Arthur ¥. Gray ; those of genitalia and lingual dentition, 
by W. G. Binney. 
PLATE I. 
Mesodon Chiloweensis : lingual dentition. 
‘ s genitalia. 
Patula Bryanti. 
Helicodiscus fimbriatus. 
Triodopsis Levettei. 
Zonites petrophilus. 
« — Wheatleyi. 
Vitrinozonites latissimus : lingual dentition. 
Arionta intercisa: lingual dentition. 
Triodopsis Copei. 
Arionta Mormonum, var. circumcarinata, 
Zonites Upsoni. 
PAU OW 
| PLATE II. 
Fig. A. Zonites placentula. 
ON) 835 ih macilentus. 
ae: “ _ cuspidatus. 
| Sen val)! ‘s Andrewsi. 
Sea: Same Wile 
Shed “  multidentatus. 
GEACK CD - significans. 
| aso a ss Rugeli: shell. 
ome |e ie e dentition. 
ie ‘sf subplanus: dentitign. 
“ K. Mesodon Chiloweensis. 
Bi s Andrewsi. 
“ M. Macrocyclis Hemphilli. ; 
\ “« N. Microphysa Stearnsi: dentition. 
SAO! ‘. oY jaw. 
