Maryland Geological Survey 361 



to name it at present. The specimen, however, has been seen by Dr. 

 Grabau who regards it as a new species. 



Length, about 28 mm. ; height, about 2~> mm. 



Occurrence. — Eomney Formationt, Hamilton Member. West of iron 

 bridge over Town Creek northeast of Oldtown. 



Collection. — Maryland Geological Survey. 



Family MYALINIDAE 



Genus MODIELLA Hall 



MoDiELLA PYGMAEA (Conrad) 



Plate XXXI, Figs. 1-5 



Pterinea pygmaea Conrad, 1842, Jour. Acad. Nat. Sci., Phila., vol. viii, p. 251, 



pL xiii, fig. 15. 

 Modiella pygmaea Hall, 1885, Pal. N. Y., vol. v, pt. i, Lamellibranchiata ii, p. 



514, pi Ixxvi, figs. 9-20. 

 Modiella pygmaea Clarke, 1903, N. Y. State Mus., Bull. 65, p. 443. 

 Modiella pygmaea Grabau and Shimer, 1909, N. Am. Index Fossils, vol. 1, p. 



456, fig. 606d. 



Description. — " Shell small, obliquely obovate ; length one-third greater 

 than the height; basal margin arcuate anterior to the middle, broadly and 

 distinctly curving to the post-inferior extremity; posterior extremity 

 obliquely and broadly curved; anterior end short, auriculate, limited by a 

 depression extending from just anterior to the beak to the basal margin 

 and producing a more or less distinct sinus. Valves very convex in the 

 middle and upper portions of the shell; beaks subanterior, small, closely 

 appressed and incurved; umbonal slope not distinctly limited, rather 

 prominent, arcuate, extending to the post-inferior extremity. Surface 

 marked by fine concentric striae, crossed by curving, radiating striae which 

 are more distinct on the body of the shell just posterior to the sinus." 

 Hall, 1885. 



Several specimens of this species were obtained from the thinner and 

 more argillaceous Hamilton shales of Maryland and ^Yest A'irginia. There 

 is apparently no marked dill'erence between these southern specimens and 

 those from the typical localities for this species in central New York. It 

 is readily identified by its shape and size, short anterior and broader 



