202 POTTS VILLE FAUNA OF OHIO 



Nucula lunulata Girty mss. 

 PL X, figs. 17-19 



Description. Another species of Nucula from the Sharon ore is 

 the same as Girty's manuscript form from the Morrow formation of 

 Arkansas, the description of which is quoted below: 



"Shell small and conspicuously triangular in shape. The width 

 and height are about equal. The convexity is great and the umbones 

 are very prominent. The cardinal and posterior parts of the shell are 

 strongly inflected long lines that are straight or slightly concave, and 

 that make with one another an angle of considerably less than 90 de- 

 grees. The inflected parts are so directed that they are concealed when 

 the shell is viewed from either side. The inferior outline is gently con- 

 vex and is directed to the two other sides in such a way that the height 

 of the shell is nearly equal to the width and the posterior outline is 

 distinctly shorter than the anterior outline. Owing to the high con- 

 vexity and strong inflection of the margins a broad flattened surface 

 is formed on the cardinal and posterior ends. This surface on the 

 posterior side is somewhat depressed and set off by angles, thus forming 

 a large 'lunule' which is very sharply defined. Nothing at all com- 

 parable to this is developed on the cardinal plane. 



"The surface is marked by very fine, regular, concentric striae. 



"This species resembles seveial that occur in such different strati- 

 graphic and geologic relations that I would hesitate to regard them as 

 the same without conclusive evidence of very close agreement. It is 

 similar to the Mississippian N. shumardana, but it is rather less elon- 

 gated transversely, and it is readily distinguished by its higher con- 

 vexity and more prominent umbones. N. wewokana, N. levatiformis 

 var. obliqua, and N. pulchella are related but distinct species." 



Remarks. N. lunulata is common in the Sharon ore at one locality 

 in Scioto County where it is associated with N. subrotundata Girty mss. 

 and N. elongata n. sp. It occurs only as internal casts. 



Horizon and locality. Sharon ore: Scioto County, Lick Run, 

 Locality 2, c. 



Nucula parva McChesney 



1860 Nucula parva. McChesney, Desc. New Pal. Foss., p. 54. 



Coal Measures: Danville, Illinois. 

 1865 Nucula parva. McChesney, 111. New Spec. Foss., PI. II, Figs. 8a-c. 



Remarks. Nucula parva is of rare occurrence in rocks of Pottsville 

 age in Ohio, but has been found to be sparingly present in the Lower 

 Mercer limestone of Perry, Muskingum, and Licking counties, and also 

 in the McArthur limestone. Several fairly well preserved specimens 



