226 POTTSVILLE FAUNA OF OHIO 



Genus Aviculopecten McCoy 

 Aviculopecten coxanus Meek and Worthen 



1860 Aviculopecten coxanus. Meek and Worthen, Proc. Acad. Nat. Sci. Phil., p. 453. 

 Coal Measures: Adams County, Illinois. 



Description. Aviculopecten coxanus is common throughout the 

 Pottsville formation of Ohio, but occurs abundantly in the Lower 

 Mercer limestone. The radiating ribs, which alternate in size, are on 

 the whole finer with wider interspaces than indicated on Herrick's 

 figured specimen from the Lower Mercer limestone of Flint Ridge. 1 The 

 form is slightly oblique with large ears which are also marked by radiat- 

 ing ribs. The entire surface is covered with fine, closely arranged, 

 concentric lines. . 



Dimensions. A large specimen from the Sharon ore measures: 

 length 13.5 mm., length of hinge line 10 mm., maximum width below 

 hinge line 13 mm. 



Horizon and locality. Harrison ore: Jackson County, Locality 1, 

 r. Sharon ore: Scioto County, Locality 2, c. Lowellville limestone: 

 Muskingum County, Locality 19, c. Boggs member: Muskingum 

 County, Locality 27, c. Widely distributed throughout the Lower 

 Mercer member, a. Upper Mercer member: Muskingum County, Lo- 

 cality 68, r. Widely distributed throughout the Me Arthur member, c. 

 Black Flint member: Jackson County, Locality 87, c; Vinton County, 

 Localities 91, 92, r. 



Aviculopecten herzeri Meek 

 PL XIII, figs. 3, 4 



1871 Aviculopecten (Streblopteria ?) herzeri. Meek, Proc. Acad. Nat. Sci. Phil., p. 61. 



Lower Coal Measures: Newark, Ohio. 

 1875 Aviculopecten (Streblopteria ?) herzeri. Meek, Pal. Ohio, Vol. II, p. 330, PL 19, 



Figs. 13 a-c. 



Lower Coal Measures: Newark, Ohio. 



Description. Aviculopecten herzeri is one of the most common and 

 characteristic pelecypods in the collections of middle and upper Potts- 

 ville fossils. It occurs most abundantly in the Lower Mercer and 

 McArthur members, but has not been found at any of the lower hori- 

 zons. The surface sculpture of fine subequal radiating and concentric 

 markings, which produce a beautifully cancellated appearance, dis- 

 tinguish it from all other forms in the Pottsville formation, except pos- 

 sibly from A. pellucidus. The latter species, however, may be dis- 

 tinguished by its difference in outline and by its smaller size. 



derrick, C. L., Bull. Den. Univ., Vol. 2, p. 26, PL 1, Figs. 4, 17, 1887. 



