30 The Fauxa of the Keysee ^Member of the 



Occurrence. — Helderberg FormatioX; Keyser Member. Keyser, 

 West Virginia ; Cash Valley, Maryland. 

 Collection. — U. S. National Museum. 



Family SPIRIFERIDAE 



Genus SPIRIFER Sowerby 



Spirifer modestus Hall 

 Plate LXVIII, Figs. 17-22 



Spirifer modestus Hall, 1859, Nat. Hist. N. Y., Pal., vol. iil, p. 203, pi. xxviil, 

 figs, la-e, 1861. 



Description. — " Shell small, subglobose. Ventral valve very gibbous 

 near the middle and towards tlie beak, having a shallow undefined sinus 

 extending from the beak to the front : beak prominent, acutely pointed, 

 incurved. Dorsal valve regularly convex, semicircular or subtriangular: 

 extremities rounded, sometimes an undefined mesial elevation: beak 

 scarcely extending above the hinge-line, not incurved; hinge-line very 

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

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

 narrow, triangular. Dental lamellse 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 coraUiiwnsis 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. — Helderberg Formation, Keyser Member. Market 

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



