664 NORTH AMERICAN INDEX FOSSILS. 



surface concave, lower rounded ; notch moderate. (This parallels 

 Ecciliopterns in the development of the high collar, and some 

 place it in that genus.) 



Beekmantown of New York, Vermont, and Canada. 



LX. Maclurea Leseur. (Maclurites Leseur.) 

 Shell a left-handed or sinistral coil of few rapidly enlarging 

 whorls, the spire flat, and the base somewhat prolonged and 

 umbilicated. Ordovicic. 

 189. M. magna Leseur. (Figs. 918, 918, A.) Ordovicic. 



Fig. 918. Maclurea magna, X %• (After Hail.) 



Large, of about six whorls, obtusely angular at outer edge, 

 breadth more than twice the height ; upper surface of whorls 

 gently convex; operculum long, parallel-sided with nucleus in 

 center of upper side. 



Chazy (middle) of New York, Virginia, Kentucky, Michigan, 

 and other southern and western localities. 



190. M. bigsbyi Hall. (Fig. 919.) Ordovicic. 

 Medium-sized, diameter about twice the height. Umbilicus 



large and abrupt, exposing about half of each of inner whorls. 

 Growth lines cancellated on periphery by revolving lines. Oper- 

 culum with nucleus at upper inner angle. 



Stones River of Wisconsin, Illinois, and Tennessee. 



191. M. logani Salter. (Fig. 920.) Ordovicic. 

 Up to 3^4 inches in diameter, of few rapidly enlarging whorls, 



the width of the outer whorl being about three times that of the 



