136 Systematic Paleontology — Middle Devonian 



Williams Eoad, ^ mile east of Queen City Hotel, Cumberland; in Jen- 

 nings Eun, ^ mile west of Corriganville ; Town Creek Eoad at George 

 Diefenbaugh's ; B. & 0. E. E. ait at 21st Bridge; on Haneock- 

 Harrisonville Eoad about 3 miles north of Hancock; McCoys Ferry; along 

 Flintstone Creek in Gilpin; on National Eoad in Gilpin; west of iron 

 bridge over Town Creek northeast of Oldtown; on road east of Pine 

 Hill about 4 miles north of Oldtown; B. & 0. E. E. cut at Hancock Sta- 

 tion, W. Ya. ; on road about half way between Eomney and Hanging 

 Eock, W. Va. 



Collections. — Maryland Geological Survev; American Museum of Nat- 

 ural History. 



Stropiieodonta demissa (Conrad) 

 Plate X, Fig. 1 



Strophomena demissa Conrad, 1842, Jour. Acad. Nat. Sci., Phila., voL viil, 



p. 258, pi. xlv, fi§. 14. 

 Strophomena (Stroplwdonta) demissa Hall, 1857, Tenth Rep. N. Y. State 



Cab. Nat. Hist., p. 137, fig. 1. 

 Strophomena demissa Rogers, 1858. Geol. Penna., vol. ii, p. 827, fig. 660. 

 Stropliodonta demissa Hall, 1858, Geol. Surv. Iowa, vol. 1, pt. ii, p. 495, pi. iil, 



flg. 5. 

 Strophodonta demissa Hall, 1867, Pal. N. Y., -vol. iv, p. 81, pi. xi, figs. 14-17; 



pi. xii, figs. 1-0 ; pi. xvii, figs. 2a-2s. 

 Strophodonta demissa Keyes, 1891, Johns Hopkins Univ. Circ, vol. xi, p. 29. 

 Stropheodonta demissa Hall and Clarke, 1892, Pal. N. Y., vol. viii, pt. i, pi. xiv, 



figs. 7-12. 

 Stropheodonta demissa Schuchert, 1897, Bull. U. S. Geol. Surv., No. 87, p. 421. 

 Stropheodonta demissa Clarke, 1903, N. Y. State Mus., Bull. 65, p. 333. 

 Stropheodonta demissa Grabau and Shlmer, 1907, N. Am. Index Fossils, vol. 



ii, p. 217, fig. 263. 



Description. — Shell medium size; semi-elliptical, generally wider than 

 long although the proportions are often nearly equal; hinge-line variable 

 in length in proportion to the width of tlie slicll below; lateral margins 

 al)i-u])tly contracted beneath the cardinal extremities, wliich are often 

 auriculate. Ventral valve regularly convex, greatest elevation nearly 

 central. Umbo small and prominent with the apex slightly incurved ; 



