Maryland Geological Survey 619 



Superfamily NUCULACEA 



Family NUCULIDAE 



Genus NUCULA Lamarck 

 NUCULA CORBrLIFOHMIS Hall 

 , Plate LX, Figs. 19-23 



Nucula corbuliformis Hall, 1870, Preliminary Notice Lamellibranchiata, 11, 



p. 2. 

 Nucula corbuliformis Hall, 1885, Pal. of N. Y., vol. v, pt. i, p. 319, pi. xlvi, 



figs. 24-34. 

 Nucula corbuliformis Grabau and Sliimer, 1909, N. Amer. Index Foss., vol. 



i, p. 396, flg. 503. 



Description. — Shell small, triangular; beak prominent acute and an- 

 terior, umbonal slopes direct. Ijength and height sometimes nearly 

 equal, anterior margin broadly rounded. Hinge-line sloping and bearing 

 denticulations on both sides of the beak. Surface convex, depressed in 

 the umbonal region; covered by fine but not conspicuous concentric striae. 



Length 9 mm.; height C nun. 



Nucula corbuliformis is common in the Hamilton shales and occasion- 

 ally occurs in the Ithaca fauna of New York. 



It is of rare occurrence in the Chemung, occasional in the Pai'khead, 

 and locally abundant in the Ithaca fauna of Maryland. 



A single specimen was found in the Ithaca fauna at Hancock which is 

 unusually gibbous and has very deep muscular scars. It is probably a 

 geroritic individual of this species. 



Occurrence. — Jennings Formation, Chemung Member. Oakland- 

 Altamont Road; Town Creek, 2328. Pabkhead Member. Williams 

 Road, on Polish Mountain, 1353; 2 miles north of mouth of Town Creek, 

 lilG abundant, 1803. Woodmont Member, Ithaca Fauna. Xational 

 Road west of Tonoloway Ridge in soft yellow argillaceous sandstone; 

 Hancock, 1149 to 137-1; Yellow Springs, West Virginia. 



Collection. — Marvland (ieolooical Survev. 



