Cumings — Morphogenesis of Platystrojphia. 21 



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1.46 



Fig. 8. Platystrophia lynx. 1-16, from Trenton Falls, N. Y. ; 32, com- 

 posite of 1-16 : 17-31, from Colby County Kentucky (Trenton) ; 33 composite 

 of 17-31; 34, composite of 1-31 ; Shell index given below each figure. All 

 natural size. Collection Yale Museum. 



