632 



NORTH AMERICAN INDEX FOSSILS. 



91. L. rectistriata Raymond. (Fig. 855.) Ordovicic. 



Distinguished by its small size, nearly straight lines of growth 

 and rather prominent carina beneath the periphery. 



FlG. 855. Lophospira rectistriata, X f • (After Raymond. ) 



Common throughout lower and middle Chazy of the Lake Cham- 

 plain region. 

 92. L. bicincta (Hall). (Fig. 856, a-d.) Ordovicic. 



Shell 15 to 30 mm. high, with apical angle about 6o°. Six 

 subangular volutions, the last ventricose-tricarinate, the lower carina 

 hidden in younger whorls. Notch in lip exceedingly shallow. 

 Growth lines sharp. 



Stones River and Trenton group of Kentucky, Tennessee, Min- 



FlG. 856. a-d, Lophospira bicincta ; e, f, L. quadrisulcata. (After 

 Ulr. and Scof., Pal. Minn.) 



nesota, Illinois, Wisconsin, New York, and Canada. Also in the 

 Cincinnati group of Minnesota. 



93. L. quadrisulcata Ulrich and Scofield. (Fig. 856, e, f.) 



Ordovicic. 

 Like L. bicincta, but with an additional carina and groove on 

 the body whorl, all grooves and carinae being more pronounced. 

 Richmond group of Minnesota. 



94. L. helicteres Salter. (Fig. 857.) Ordovicic. 

 Whorls bicarinate, intercarinal spaces concave ; embracing to 



lower carina except last whorl, which is free, and which has an 

 additional carina formed by the sutural margin. 



Black River of Ontario, Kentucky, and Wisconsin. 



