Genus Leda Shumacher 

 Leda bellistriata Stevens 



1858 Leda bellistriata. Stevens, Am. Jour. Sci., 2nd Ser., Vol. 25, p. 261. 



Coal Measures: Danville, Illinois; Summit, Ohio. 

 1915 Leda bellistriata. Girty, U. S. Geol. Surv., Bull. 544, p. 122, PL XIV, Figs. l-9a. 



Wewoka formation: Oklahoma. 



This shell with its fine, concentric markings appears in the Lowell- 

 ville limestone and continues throughout the remainder of the Potts- 

 ville rocks, but has nowhere been found in considerable numbers. 

 It is common in the Lower Mercer limestone, especially on Flint 

 Ridge, where it was reported by Herrick to occur abundantly, l but 

 in the collection from that locality studied for the present report, 

 such was not found to be the case. The specimens from Ohio compare 

 closely with those figured by Girty from the Wewoka formation of 

 Oklahoma, but are on the average smaller. A large specimen from 

 the Lowellville limestone measures: length 10.5 mm., height 5.5 mm. 



Horizon and locality. Lowellville limestone: Poverty Run, 

 Muskingum County (Locality 19), r. Boggs limestone: near Hope- 

 well P.O., Muskingum County (Locality 26), r. Throughout middle 

 and upper Potts ville members. 



Leda prolongata n.sp. 

 PL IV, Fig. 20 



Description. Shell large for specimens of this genus, elongate- 

 ovate in outline with the posterior end greatly produced; depressed 

 convex, the greatest convexity being in the anterior part below the 

 umbones but becoming gradually and regularly less to the posterior 

 tip. Beaks prominent and incurved, situated from one-third to one- 

 fourth the length of the valve from the anterior margin; cardinal 

 margin posterior to beaks strongly concave; anterior margin rounded 

 and curving regularly into the rounded base; posterior portion slender, 

 tapering to a sharp point, and greatly extended; umbonal ridge prom- 

 inent and elevated. Surface of shell marked by very fine, regular, 

 rounded concentric lines. 



Dimensions. The holotype from the Lower Mercer limestone 

 measures: length 41 mm., height 16 mm., convexity of right valve 

 2.5 mm. (compressed); a single small individual from the Boggs lime- 

 stone measures: length 22.5 + mm., height 9. 5 mm., convexity 2.5 

 mm. 



Remarks. This species is characterized by its large size, its slen- 

 der form, and its extended posterior portion. It is very rare and 

 is represented in the Pottsville collections by only two individuals, 

 one from the Lower Mercer limestone, and another smaller specimen 

 from the Boggs which is imperfect in lacking the posterior tip. Con- 



iHerrick, C. L., Bull. Den. Univ., Vol. 2, p. 40, 1887. 



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