274 Systematic Paleoxtology — Middle Deyoxiax 



Cypricardella bellistriatiis Grabau, 1S99, Bull. Buffalo Soc. Nat. Sci., vol. vi, 



p. 252, fig. 169. 

 Microdon (Cyijricardella) bellistriatus Clarke, 1903, N. Y. State Mus., Bull. 



65, p. 439. 

 Cypricardella bellistriata Cockerell, 1905, Am. Geol., vol. xxxvi, p. 330. 

 Cypricardella bellistriata Grabau and Shimer, 1909, N. Am. Index Fossils, 



vol. i, p. 535, figs. 727c, d. 



Description. — "Shell of medium size or larger; form subrhomboidal 

 to subelliptical ; extremely variable proportions of length and height vary- 

 ing from a length of twice the height, to a length of less than one-third 

 greater than the height; basal margin regularly curving anteriorly, often 

 nearly straight in the posterior half; posterior margin almost vertically 

 subtruncate, sometimes gently curving; anterior end narrowed, prolonged 

 below and abruptly rounded at the extremity, constricted above by a dis- 

 tinct lunule; cardinal line nearly straight. Valves depressed-convex, 

 becoming moderately convex in the umbonal region ; beaks usually at about 

 the anterior third, but often nearer the anterior extremity, small, closely 

 appressed, scarcely rising above the hinge-line; ujnbonal slope continued 

 as a low undefined ridge to the post-basal angle. Test of moderate 

 thickness, marked by strong, even, angular striae, which continue nearly 

 uniform in character over the entire shell." Hall, 1885. 



This species is common in the thinner, somewhat arenaceous Hamilton 

 shales of Evitts Creek below Wolfe Mill. The specimens agree closely in 

 form and markings with those figured from New York and they present 

 similar variations in reference to the proportions of length and height. 

 It was identified by Hall from the Hamilton shales near Cumberland, 

 Md. (Pal. N. Y., vol. v, pt. 1, Lamellibranchiata ii, p. 309) and the 

 cardinal view of a specimen from this locality is figured (pi. xlii, fig. 17). 

 The species is readily recognized by its form ; nearly vertically truncate 

 posterior end; projecting lower part of anterior end; and strong, even, 

 angular concentric striae. 



Length, 26, 30, 34 mm.; height, 21, 20, 2C mm. 



Occurrence. — Eomney Formattox, Hamilton Member. East bank 

 Evitts Creek below Wolfe Mill; Williams Eoad, | mile east of Queen City 

 Hotel, Cumberland; B. & 0. E. E. cut at 21st Bridge; along Flintstone 

 Creek in Gilpin. 



