400 Systematic Paleontology 



short, rounded at tlie cardinal extremities. Area triangular, faintly de- 

 fined, about half the width of the shell, arcuate. Foramen of medium size, 

 narrow, triangular. Dental lamellge slightly diverging, and extending 

 more than half way to the base of the shell. Surface marked by faint 

 concentric lines of growth." Hall, 1859. 



This species was described by Hall from specimens found at Cumber- 

 land. As found in the Keyser of Maryland it corresponds to Spirifer 

 corallinensis the typical spirifer of the New York Cobleskill. There is a 

 close relationship between these two forms. Spirifer modestus differs 

 chiefly from Spirifer curallinensis in its extremely shallow sinus and 

 faint fold, and in the absence of distinct plications. It is also closely 

 related to Spirifer eriensis from which it differs in having its beak much 

 curved, cardinal slopes quite concave, greatest width two-thirds the dis- 

 tance from the front, cardinal angles rounded, and in being without 

 plications. 



Occurrence. — Heldeebeeg Formation, Keyser Member. Market 

 Street Bridge Cumberland, southwest of Eawlings, Pinto, Cash Valley, 

 Devil's Backbone, Tonoloway, Flintstone, Hancock, Breakneck Hill 

 Allegany County, Maryland; Hyndman, Pennsylvania; Cedar Cliff, 

 Knobly Mountain, Keyser, West Virginia. 



Collection. — Maryland Geological Survey. [Maynard.] 



Spirifer modestus var. plicatus n. var. 

 Plate LXVIII, Figs. 23, 24 

 Description. — Shell large in comparison with the typical form of S. 

 modestus; subglobose, somewhat transverse. Ventral valve very gibbous 

 toward the beak, greatest convexity about two-thirds the distance from 

 front to beak. Sinus usually well defined, extending from the beak to the 

 front; beak prominent, pointed and incurved. Dorsal valve regularly 

 convex, gibbous, greatest convexity just anterior to the beak; beak in- 

 curved scarcely extending above the hinge-line; extremities of thn shell 

 rounded and with a well-defined mesial elevation. Area triangular, 

 faintly defined, about one-half the width of the shell. Surface marked 

 by three or four indistinct plications on each side of the fold and sinus, 

 and by faint concentric lines of growth. 



