which they resemble most closely in contour. Height 5.5 mm., 

 height of last volution 3 mm., width of last volution 3 mm. 



Horizon and locality. Harrison ore: Jackson County (Locality 



D,c. 



Sphaerodoma primigenia (Conrad) ? 



1835 Stylifer primogenia. Conrad, Trans. Geol. Sec. Penn., Vol. 1, p. 267, PL 12, 

 Fig. 2. 



A single internal cast of a small gastropod from the Sharon ore 

 has been placed with the above species. As may be seen by the 

 following measurements, the form from the Sharon ore is much smaller 

 than even small specimens of S.primigenia. Height 12 mm., height 

 of last volution 7 mm., width of last volution 10 mm. 



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

 (Locality 2), r. 



PHYLUM MOLLUSCA 



Class Cephalopoda 



Genus Orthoceras Breynius 



Orthoceras n.sp. 



Description. A small, gradually tapering Orthoceras from the 

 Sharon ore represents in all probability a new species, but the material 

 at hand is too poor for descriptive purposes. The siphuncle is con- 

 spicuously eccentric, and the septa which are strongly convex, are 

 situated at any given point about one-fourth the diameter of the 

 shell from each other. 



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

 (Locality 2), c. 



Orthoceras n.sp. 



Several crushed specimens of a large Orthoceras from the Lowell- 

 ville and Lower Mercer members apparently belong to the same 

 species which is undescribed. The material at hand, however, is too 

 poor and fragmentary for description and figuring. The form appears 

 to be gradually tapering, but other characters, such as the position 

 of the siphuncle and the ratio of the height of the chambers to their 

 diameter cannot be determined. The species can be most readily 

 compared with O.fanslerensis Keyes and Oxolletti Miller, but they 

 can be distinguished from the Ohio form by the greater height of 

 their chambers. 



Horizon and locality. Lowellville member ? : Holbein, Mus- 

 kingum County (Locality 20) r. Lower Mercer: Little Mill Creek, 

 Mahoning County, r. 



86 



