

634 



NORTH AMERICAN INDEX FOSSILS. 



New York and Ottawa River, Canada (" Black River" group). 

 Chazy of New York. 



97. L. acuminata Ulrich and Scofield. (Fig. 859, d.) 



Ordovicic. 



With sharper periphery and lower carina than preceding, more 

 numerous whorls and smaller apical angle ; no umbilicus. 



Richmond group of Indiana, Ohio, and Minnesota. 



Fig. 859. a-c, Lophospira perangulata ; d, L. acuminata; e-h, L. medialis ; i-k, 

 L. pulchella. (After Ulrich, Pal. Minn.) 



98. L. medialis Ulrich and Scofield. (Fig. 859, e-h.) 



Ordovicic. 



Embracing to near periphery; apical angle 58 to 70 ; lower 

 carina faint ; umbilicus small. 



Trenton of New York, Minnesota, Kentucky, Tennessee, and 

 Missouri. 



99. L. pulchella Ulrich and Scofield. (Fig. 859, i-k.) 



Ordovicic. 



With well-marked subsutural carina, concave shoulder and 

 lower carina strong and obtuse ; angle 50 to 56 ; umbilicus 

 minute or closed. 



Black River of Minnesota, Trenton of Kentucky. Variety with 

 smaller angle (50 to 46 ) in Richmond of Minnesota. 



100. L. oweni U. and S. (Fig. 860, a-c.) Ordovicic. 

 Subsutural carina broad and obscure ; band thick, rounded ; 



shoulder less concave than preceding ; lower carina obsolete in 

 adult. 



Stones River and Black River groups of Kentucky and Min- 

 nesota, and a variety in Eden of Ohio. 



