224 NORTH AMERICAN INDEX FOSSILS. 



larger series near ventral border and becoming obsolete before 

 reaching the strong, rounded keel. 

 Lower Washita of Texas, etc. 



392. S. inflata (Sowerby). Comanchic. 

 Large, of regularly enlarging, very slightly embracing and 



coarsely costate whorls, the costse in last whorl more than their 

 width apart, with a coarse node at ventral margin and another just 

 below ; keel prominent, scarcely bounded by grooves. 



Horsetown of California and British Columbia, and equivalent 

 horizon in Europe, India, etc. 



393. S. belknappi Marcou. (Fig. 1504.) Comanchic. 



Fig. 1504. Schloenbachia belknappi, about one fourth natural size. (After Hill.) 



Ribs increase by occasional bifurcation and intercalation; tuber- 

 cles absent; in adult the ribs are flexuous, and become very broad 

 before ending near the pronounced keel, where they have an alter- 

 nating position. 



Lower Washita of Texas. 



394. S. propinqua Stoliczka. Comanchic. 



From 40-44 ribs on a single whorl with tendency to bifurcation 

 near umbilical margin; keel at first simple, later broken up into 

 slight undulations; differs from 5*. helknappi in the larger umbil- 

 icus, more pronounced keel and tubercles near umbilicus. 



Queen Charlotte formation (Horsetown) of Queen Charlotte 

 Islands ; Ootatoor beds of India. 



