436 Systematic Paleontology 



Occurrence. — Helderberg Formatiox, Keyser Member. Pinto, Cash 

 Valley, Viaduct Cumberland, Tonoloway. New Scotland Member. 

 Common at Devil's Backbone, Corriganville, Maryland; Iveyser, West 

 Virginia. 



Collection. — Maryland Geological Survey. 



RhYNCHOSPIRA FORMOSA Hall 



Plate LXXII, Figs. 26-30 



Waldheimia formosa Hall, 1857, 10th Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 88. 

 Trematospira formosa Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 215, pi. 



xxxvi, figs. 2a-t, 1861. 

 Rhynchospira formosa Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 485, pL 



xcva, figs. 7-11, 1861. 



Description. — " Shell longitudinally ovate. Ventral valve tapering 

 towards the beak : beak prominent, rounded, arched or incurved, truncated 

 at the apex by a round perforation, one side of which is formed by the 

 deltidium. Dorsal valve gibbous, sometimes most prominent near the 

 umbo : beak closely incurved beneath the opposite one. Surface marked 

 by eighteen to twenty-two or twenty-three simple rounded or rarely sub- 

 angular plications, two or three of which are much smaller and slightly 

 depressed on the middle of each valve, so as to form a faint narrow sinus 

 extending nearly or quite to the apex of the beaks, and giving a slight 

 emarginate outline to the front. Surface marked by fine imbricating con- 

 centric lines of growth, which become strong lamellae towards the margins 

 of the shell: shell granulose." Hall, 1859. 



Length 1.5 cm. ; width 1.4 cm. 



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

 Backbone, Cash Valley, Tonoloway, Cookerly, | mile east of Eush, Marj'- 

 land ; Keyser, West Virginia. 



Collection. — Maryland Geological Survey. 



[Maynard.] 



