DESCRIPTION OF SPECIES 193 



v 



valve 5 mm.; an individual of average size from the Lower Mercer lime- 

 stone has the following dimensions: length 24 mm., width 22 mm., con- 

 vexity 12 mm. 



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

 c. Sharon ore: Scioto County, Locality 2, c. Of general distribution 

 in the Lowellville, Boggs, Lower Mercer limestone, Lower Mercer ore, 

 Upper Mercer, McArthur, and Black Flint members, aa. 



Composita sp. 



Description. A species of Composita, closely related to C. subtilita, 

 occurs at several localities in the Boggs, Upper Mercer, and McArthur 

 members. The form is " relatively shorter and broader than is char- 

 acteristic of C. subtilita , with the fold and sinus much less strongly 

 marked. However, the specimens at hand are for the most part too 

 poorly preserved for specific identification. 



Horizon and locality. Boggs member: Muskingum County, Lo- 

 cality 26, r. Upper Mercer member: Mahoning County, Locality 76, 

 r. McArthur member: Jackson County, Locality 80, c; Vinton County, 

 Locality 83, r. 



PHYLUM MOLLUSCA 



Class Pelecypoda 

 Minute Pelecypoda (Three or more species) 



Description. Several species of minute pelecypods are common in 

 the Sand Block ore. They are pleurophoroid in form and occur as 

 internal molds measuring from .5 to 1.5 mm. in length; none of the 

 surface markings are* preserved. 



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

 57, c. 



Genus Solenomya Lamarck 

 Solenomya radiata Meek and Worthen 



1860 Solenomya radiata. Meek and Worthen, Proc. Acad. Nat. Sci. Phil., p. 547. 



Coal Measures: GrayviUe, Illinois. 

 1866 Solenomya radiata. Meek and Worthen, Geol. Surv. 111., Vol. 2, p. 349, PI. 26, 



Figs. lOa, b. 



Coal Measures: Schuyler County, Illinois. 



Description. This species is rare in the Pottsville formation of 

 Ohio, but occurs most commonly in the Lower Mercer limestone of 

 Muskingum and Licking counties, especially along Flint Ridge. Most 



