Maryland Geological Sukvly 275 



Collections. — Maryland Geological Surve}-; American ]\Iuseuin of Xat- 



ural History. 



Cypricardella tenuistriata (Hall) 



Plate XXXIV, Fig. 5 



Microdon tenuistriata Hall, 1870, Prelim. Notice Lamelllbranchiata 2, p. 32. 

 Microdon (Cypricardella) tenuistriatus Hall, 1885, Pal. N. Y., vol. v, pt. i, 



Lamelllbranchiata 11, p. 310, pi. xlil, flg. 16; pi. Ixxlll, figs. 23-30; pi. 



ixxiv, figs. 20, 21. 

 Microdon tenuistriatus Clarke, 1903, N. Y. State Mus., Bull. 65, p. 443. 

 Cypricardella tenuistriata. Grabau and Shimer, 1909, N. Am. Inrtex Fossils, 



vol. i. p. 534, figs. 727a, b. 



Description. — ■" Shell large, qnadrangularly subovate ; length one- fourth 

 greater than the height; ba=al margin regularly curving; posterior margin 

 subtruncate, from oblique to nearly vertical and gently curving; anterior 

 end rapidly declining from the beak and abruptly rounded below; car- 

 dinal line gently arcuate. Valves depressed-convex below, rising into 

 moderate convexity in the iimbonal region; beaks at about the anterior 

 third, small and appressed, rising a little above the hinge-line; umbonal 

 slope scarcely defined, extending in a slightly arching direction to the 

 post-basal extremity. Test thin, marked by fine, unequal, concentric 

 striae, which are at intervals raised into lamelliform undulations." Hall, 

 ISSf). 



A much smaller number of specimens belonging to this species was 

 found than of C. hellistriata. Several characteristic specimens, however, 

 were obtained and a figure of a cardinal view of a specimen of this 

 species from the Hamilton group, at Cumberland, Md., was given by 

 Hall (Pal. X. Y., vol. v, pt. 1, Lamellibranchiata ii, pi. xlii, fig. 16). 

 This species is readily distinguished from C. hellistriata by its larger size ; 

 more strongly curving basal line; less prominent umbonal slope; and 

 finer and less clearly defined striae. 



Length, 42 mm.; height, 29 -\- mm. 



Occurrence. — Eomney" Formation, Hamilton Member. Williams 

 Eoad f mile east of Queen City Hotel, Cumberland ; on Hancock-Har- 

 risonville Eoad about 2 miles north of Hancock. 



Collections. — Maryland Geological Survey; American Museum of Xat- 

 ural Historv. 



