DESCRIPTION OF SPECIES 247 



constituting almost two-thirds of the entire spire. The height of the 

 shell measures .75 mm. The second species is a high-spired, slender, 

 gradually tapering form, about .5 mm. in height, while the third be- 

 longs to the Bellerophontidae and measures less than 1 mm. in diameter. 

 Horizon and locality. Sand Block ore: Jackson County, Locality 

 57, a. 



Family Bellerophontidae McCoy 



Shells belonging to the Family Bellerophontidae are the best 

 represented group of gastropods in the Potts ville formation in Ohio. 

 The following genera are present, Bellerophon, Euphemus, Pharki- 

 donotus, Patellostium, and Bucanopsis; among these the genus Pharki- 

 donotus is the most abundant while Bellerophon and Euphemus are 

 most widely distributed. No fossils are more numerous in the Harrison 

 and Sharon ores than the Bellerophon-like shells which can be obtained 

 in an almost perfect condition. They are diminutive in size and occur 

 as internal casts so that in most cases even the generic position is unde- 

 terminable. In only a few instances, however, is surface sculpture 

 sufficiently well shown to disclose the generic and specific relations. 

 Representatives of this family constitute the most common group of 

 gastropods in the marine limestones, and hold an especially important 

 position in the Lower Mercer and McArthur members. 



Genus Bellerophon Montfort 

 Bellerophon crassus Meek and Worthen 



1860 Bellerophon crassus. Meek and Worthen, Proc. Acad. Nat. Sci. Phil., p. 458. 

 Lower Coal Measures: Pittsburgh, St. Clair County, Illinois. 



Remarks. Several of the numerous small Bellerophon-like forms 

 from the Harrison and Sharon ores show a narrow slit band with faint 

 transverse lines marking the surface, and have been referred provision- 

 ally to B. crassus. The species has not been found in any other Potts- 

 ville horizon below the Lower Mercer member; it is, however, relatively 

 common in the middle and upper Pottsville formation, especially in 

 the Lower Mercer limestone of Muskingum and Licking counties. 



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

 a. Sharon ore: Scioto County, Locality 2, a. Widely distributed in 

 the Lower Mercer member, especially in Muskingum and Licking 

 counties, c. McArthur member: Jackson County, Locality 80, c; 

 Vinton County, Localities 83, 84, c. 



