9 o 



Cincinnati Society of Natural History. 



EXPLANATION OF PLATE IV. 



A. — Pupa contracta Say. c. Central tooth, i. First lateral. 7, 9, 

 Marginals. jo. Jaw. 



B. — Limnsea caperata Say. c. Central tooth. 1. First lateral. 8, 

 10, Transition teeth. 12, 14, 15, Marginal teeth. 



C. — Limnsea desidiosa Say. 17, Transition tooth. 21,22,24, Mar- 

 ginal teeth. 35, Outer marginal. 



D. — Limnsea palustris Miiller. Abnormal first lateral. 



E. — Planorbis trivolvis Say. c. Central tooth. 1, First lateral. 

 8, Transition tooth. 14, Marginal tooth. 



F. — Planorbis bicarinatus Say. 1, First lateral. 9, Transition tooth. 

 12. Marginal tooth. 



G. — Planorbis campanulatu<" Say. F'irst lateral. 

 I. — Limnsea columella Say. Jaw. 



J. — Planorbis parvus Say. c. Central tooth. 1, First lateral. 9, 



Transition tooth. 10, 12, 13, Marginal teeth. 

 All but A, 10 and I X 600. 



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