Maryland Geological Survey 349 



StENOCHISMA FORMOSA (Hall) 

 I'late LXII, Figs. 35--39 



Rhynchonella formosa Hall, 1859, 10th Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 76, figs. 1-5. 

 Rhynchonella formosa Hall, 1859, Pal. N. Y., vol. ill, p. 236, pi. xxxv, figs. 6a-?/. 



1861. 

 Rhijnchotrcma formosinn Schuchert, 1897, Bull. U. S. Geol. Survey, No. 87, 



p. 369. 



Description. — " Shell subtriangular or transversely oval ; lateral mar- 

 gins forming an angle at the beak of about 90° to 110°. Ventral valve 

 somewhat more depressed than the opposite : beak prominent, arched, not 

 strongly incurved. Dorsal valve larger, declining with a gentle curve 

 towards the margins : beak incurved. Surface marked by twenty to 

 twenty-four simple angular plications on each valve, from two to four of 

 which in the middle are coarser and depressed in the ventral valve, having 

 a corresponding number abruptly elevated upon the dorsal valve; con- 

 centrically marked by fine closely arranged striae." Hall, 1859. 



The specimens referred to this species differ but little from those re- 

 ferred to S. deckerensis, the chief distinguishing feature being the more 

 transverse form of the latter species. 



Occurrence. — Heldekberg Formation, Keyser Member. Devil's 

 Backbone, Miller's Spring, Viaduct and Market Street Bridge Cumber- 

 land, Cash Valley, 1^ miles northeast of Flintstone, Pinto, Flintstone, 

 Maryland; Hyndman, Pennsylvania. 



Collection. — Maryland (ioological Survey. 



[Maynard.] 



Stenochisma deckerensis (Weller) 



Plate LXIII, Figs. 1-i 



Rhynchonella deckerensis Weller, 1903, Geol. Survey, N. J., Pal., vol. ill, p. 

 234, pi. xxi, figs. 1-4. 



Description: — " Shell subtriangular, wider than long, the postero- 

 lateral margins sloping from the beak, where they form an angle of from 

 9.j°-115°, in nearly straight linos to a point a little posterior to the middle 



