.lli;i.i)i:iiiii;i;(i Foii.ma i lo.x in Makyi.axd 31 



Devil's Backbone, Tonoloway, Flintstone, Hancock, Broaknt'ck Hill 

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

 Knobly Mountain, Keyser, West Virginia. 

 CoJlection. — Maryland Geological Survey. 



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 th(> slioll 

 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. 



Length 1.5 cm. ; width 1.8 cm. 



This variety differs from the typical form in having a well-developed 

 sinus and mesial fold and much more pronounced plications. 



It also resembles S. vanuccemi var. prognosticus, but differs from the 

 latter in its much greater size and absence of spiniferous surface. 



Occurrence.— Helberberg Formation, Keyser Member. Keyser, 

 West Virginia. 



Collection. — Maryland Geological Survey. 



Spirifer octocostatus Hall 

 Plate LXVIII, Figs. 2-5-29 



Spirifer octocostatus Hall, 18.57, 10th Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 62. 

 Spirifer octocostatus Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 205, pi. 



xxviii, figs. 4a-e, 1861. 



Description. — " Shell subglobose : valves nearly equally convex. Ven- 

 tral valve most elevated near the beak : sinus angular, extending to the 



