134 Systematic Paleontology — Middle Devonian 



strongly impressed muscular scar, deepest anteriorly, somewhat resemb- 

 ling the impression of a bovine hoof." Kindle, 1912. 



Occurrence. — Eomney Formation, Onondaga Member. Williams 

 Koad, 3^ miles east of Cumberland. 



Collection. — U. S. National Museum. 



[E. M. Kindle.] 



Order PROTREMATA 



Superfamily STROPHOMENACEA 

 Family STROPHOMENIDAE 



Genus STROPHEODONTA Hall 



Steopheodonta (Leptostrophia) perplana (Conrad) 

 Plate IX, Figs. 11-17 



Strophomena perplana Conrad, 1842, Jour. Acad. Nat. Sci. Phila., vol. viii, 



p. 257, pi. xiv, fig. 11. 

 Strophomena (Strophodonta) fragilis Hall, 1857, Tenth Rep. N. Y. State Cab. 



Nat. Hist., p. 111. 

 Strophomena perplana Rogers, 1858, Geol. Penna., vol. ii, pt. ii, p. 827, fig. 665. 

 Strophodonta fragilis Hall, 1858, Geol. Iowa, vol. i, pt. ii, p. 496, pi. iii, fig. 6. 

 Strophodonta perplana Hall, 1867, Pal. N. Y., vol. iv, pp. 92, 98, pi. xi, fig. 22; 



pi. xii, figs. 13-15; pi. xvil, figs, la-lo. 

 Strophodonta perplana Kcyes, 1891, Johns Hopkins Univ. Circ, vol. xi, p. 29. 

 Stropheodonta (Leptostrophia) perplana Hall and Clarke, 1892, Pal. N. Y., 



vol. viii, pt. i, p. 288, pi. xv, figs. 2-13. 

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



425. 

 Leptostrophia perplana Clarke, 1903, N. Y. State Mus., Bull. 65, p. 243. 

 Stropheodonta (Leptostrophia) perplana Grabau and Shinier, 1907, N. Am. 



Index Fossils, vol. ii, p. 217, fig. 264. 



Description. — Shell small to medium size, very thin, semielliptical ; 

 slightly concavo-convex, and frequently nearly flat ; hinge-line equaling or 

 often a little greater than the width of the shell below, cardinal extremi- 

 ties usually somewhat salient ; margins of the shell often a little contracted 

 just below the cardinal extremities, making the width less than below ; 

 but the sides are frequently nearly straight for half their length, with 

 the front broadly rouiidefl. Ventral valve slightly convex, the greatest 



