6 3 6 



NORTH AMERICAN INDEX FOSSILS. 



Upper Nashville of Tennessee; Lorraine and Richmond of 

 Ohio, Indiana, and Kentucky. 



105. L. augustina Billings. (Fig. 861.) Ordovicic. 



Large, with 8 to 10 strong volutions, up to 

 120 mm. in height; apical angle 33 to 40 , 

 embracing to within two thirds shoulder width 

 of periphery (to within one third in var. min- 

 nesotensis Ulrich and Scofield). 



Quebec group of Newfoundland ; Trenton 

 of Minnesota and Ottawa, Canada. 

 106. L. serrulata Salter. (Fig. 862, d, e,f.) 



Ordovicic. 

 Very sharply carinate with intercarinal 

 spaces deeply concave ; shoulder carina in 

 upper third, two nearly equidistant carinae on 

 body whorl ; final whorls generally free ; some 

 specialized varieties scarcely coiled. 



Stones River beds of Minnesota, Wiscon- 

 sin, Illinois ; Black River of Wisconsin, Ten- 

 nessee, and Ottawa River, Canada. 

 107. L. bispiralis (Hall). Siluric. 



Apical angle about 6o°, whorls embracing so as to leave body- 

 space equal to one half or two thirds the shoulder width ; band, 



Fig. 861. Lophos 

 pira augustina, X Z A 

 (After Billings.) 



Fig. 862. a-c, Lophospira bowdeni ; d, e, L. serrulata; f, L. serrulata var. laxa. 

 (After Ulrich, Pal. Minn.) 



which is concave, bordered by raised line, and at the center of 

 the body whorl ; shoulder nearly flat, with median carina, strong 

 in young but faint in adult individuals. Emargination slight. 



