Maryland Geological Survey 183 



Hanging Rock, W. Va. ; on the Romney-Hanging Rock Road about i/^ 

 mile north of Romney, W. Va. 



Collections. — Maryland Geological Survey; New York State Museum. 



Superfamily SPIRIFERACEA 

 Family ATRYPIDAE 



Genus ATRYPA Dalman 



Atrypa reticularis (Linne) 



Plate XVI, Figs. 4-6 



Anemia reticularis Linne, 1767, Systema Naturae, ed. xii, vol. i, p. 1132. 

 Atrypa chemungcnais Conrad, 1842, Jour. Acad. Nat. Sci. Phila., voL viii, p. 



265. 

 Atrypa chemungensis Vanuxem, 1842, Geol. N. Y., pt. iii, p. 182, fig. 4. 

 Terebratiila reticularis Hall, 1849, Am. Jour. Sci., 2d ser., vol. xx, p. 227. 

 Atrypa reticularis Hall, 1852, Pal. N. Y., vol. ii, p. 72, pi. xxiii, fig. 8; p. 270, 



pi. IV, flg. 5. 

 Atrypa reticularis Hall, 1859, Pal. N. Y., vol. iii, p. 253, pi. xlii, flg. 1. 

 Atrypa reticularis Hall, 1867, Pal. N. Y., vol. iv, p. 316, pi. Iii, figs. 1-3, 7-12; 



pi. liii, figs. 3-19; pi. liii A, figs. 22, 23. 

 Atrypa reticularis Nicholson, 1874, Rep. Pal. Ontario, p. 79. 

 Atrypa reticularis Nettelroth, 1S89, Kentucky Fossil Shells, p. 91, pi. xiv, 



figs. 12-23; pi. XV, flg. 1. 

 Atrypa reticularis Hall and Clarke, 1893, Pal. N. Y., vol. viii, pt. ii, p. 165, 



flg. 153; pi. Iv, figs. 1-17. 

 Atrypa reticularis Schuchert, 1897, Bull. U. S. Geol. Surv., No. 87, p. 154. 

 Atrypa reticularis Clarke, 1903, N. Y. State Mus., Bull. 65, p. 195. 

 Atrypa reticularis Grabau and Shimer, 1909, N. Am. Index Fossils, vol. i, 



p. 310, figs. 389a, 389b, 392a-c. 



Description. — Shell large but variable in form and dimensions; iisu- 

 ally oblong-ovate, with the greatest width a little below the hinge-line. 

 Ventral valve usually moderately convex near the umbo, flattened toward 

 the sides, and markedly depressed in front, with occasionally a broad but 

 shallow sinus towards the front margin; beak small, incurved, and per- 

 forated by a small foramen. Dorsal valve convex, always more so than 

 the ventral, and frequently very gibbous; greatest convexity near the 

 middle, from which it slopes abruptly to the lateral margins; generally 

 without a mesial fold corresponding to the sinus of the ventral valve. 

 Surface marked by clear rounded or sub-angular plications, which in- 



