654 



NORTH AMERICAN INDEX FOSSILS. 



159. S. remota Bill. (Fig. 895, a, b.) Cambric. 

 Small, with low spire of three whorls sometimes slightly angular 



at outer margin ; height 4.5 to 6.75 mm., width 6.75 to 9 mm. 



Lower Cambric (Etcheminian) of Newfoundland and eastern 

 Massachusetts. 



160. S. primaeva (Bill.). (Platyceras primcevum Bill.) (Fig. 

 895, c.) Cambric. 

 Minute ; spire depressed ; last whorl partly free. (Some spec - 



Fig. 895. a, b, Straparollina remota ; c, S. primczvum. (After Walcott, loth Ann. 



Rep. U. S. G. S. ) 



mens show deep dorsal sinus, while others appear to be without 

 it (Massachusetts). These may represent distinct groups of 

 phylogerontic shells in which the power to coil becomes obsolete.) 

 Lower Cambric (Georgian) of Quebec, and Troy, N. Y. Etch- 

 eminian of eastern Massachusetts. 



L. Straparollus Montfort. 

 Shells varying from broadly turbinate to discoidal, with rounded 

 whorls without sinus, and with broad umbilicus. Siluric(?)-Jurassic. 

 161. S. clymenioides Hall. (Fig. 896.) Devonic. 



Fig. 896. Straparollus clymenioides. 

 (After Hall, N. Y., V.) 



Fig. 897. Straparollus rudis, X %• 

 (Copy from Hall.) 



Four to five gently enlarging volutions almost in same plane, 

 slightly compressed ; diameter 1 to 2 inches. 



Schoharie of New York ; Decewville of Canada. 

 162. S. rudis Hall. (Fig. 897.) Devonic. 





