GASTROPODA— PLEUROTOMARIIDM. 



641 



119. L. vitruvia (Bill.). (Fig. 871, h-k.) Ordovicic. 



Larger than preceding, with stronger, backward deflected lines 



of growth and more strongly defined band. Umbilicus open and 



Fig. 871. a-d, Liospira micula [d, surface enlargement); e-g, L. progne ; h-k r 

 L. vitruvia (g and k — longitudinal sections showing hollow axis). (After Ulrich 

 andScof., Pal. Minn.) 



often a third of the diameter of the shell. Lower lip with tongue- 

 ike projections. 



Stones River to Trenton ; Canada, New York, Tennessee, Ken- 

 tucky, Ohio, Indiana, Illinois, Iowa, Wisconsin, and Minnesota. 

 120. L. americanus (Bill.). Ordovicic. 



Differs from L. vitruvia in more rounded lower lip, as shown by 

 lines of growth. Umbilicus wider and less abrupt and without 

 angulation. 



In the Trenton limestones of eastern Canada, New York, Min- 

 nesota, and Manitoba ; Stones River and Black River of Tennessee. 



Fig. 872. Liospira eugenia. ( After Billings. ) 



121. L. eugenia (Bill.). (Fig. 872.) Ordovicic. 



Shoulder convex near suture, concave near periphery ; periphery 

 elevated ; umbilicus closed. 



