DESCRIPTION OP SPECIES 159 



Horizon and locality .^-Lower Mercer limestone: Muskingum 

 County, Localities 43, 45, r; Licking County, Locality 48, r. 



Fenestellidae undetermined 



Remarks. Bryozoans belonging to the family Fenestellidae are 

 present in the middle and upper Pottsville formation, but are too 

 poorly preserved even for generic identification. 



Horizon and locality. Lower Mercer limestone: Perry County, 

 Locality 35, c. Upper Mercer member: Perry County, Locality 63, c; 

 Coshocton County: Locality 70, c. McArthuf member: Vinton County, 

 Locality 84, c; Hocking County, Locality 86, c. Widely distributed 

 throughout the Black Flint, c. 



Genus Fenestella Lonsdale 

 Fenestella delicatula Ulrich 



1890 Fenestella delicatula. Ulrich, Geol. Surv. 111., Vol. 8, p. 549, PI. 52, Fig. 2. 

 Base of Coal Measures: Seville, Illinois. 



Remarks. A few specimens in very close agreement with Ulrich's 

 species, Fenestella delicatula, were obtained from the Black Flint mem- 

 ber at a single locality in Vinton County. The state of preservation 

 is somewhat imperfect, but as nearly as can be observed no important 

 differences exist between the two forms. 



Horizon and locality. Black Flint: Vinton County, Locality 92, r. 



Fenestella limbata Foerste 



1887 Fenestella limbatus. Foerste, Bull. Den. Univ., Vol. 2, pp. 83, 87, PI. 7, Figs. 10 a-d. 

 Coal Measures: Flint Ridge and Bald Hill, Ohio. 



Description. This species is common in the Lower and Upper 

 Mercer limestones, especially of Muskingum and Licking counties, 

 but has not been obtained from any of the other members of the Potts- 

 ville formation. The size varies within wide limits, and the species 

 includes fine, delicate forms as well as those which are considerably 

 coarser. It is characterized by small, rather closely arranged nodes on 

 the median keel, and by unusually large, regularly arranged pores on 

 either side, so situated that one generally occurs opposite each dis- 

 sepiment, and another half-way between each dissepiment. On ac- 

 count of their large size, these pores project laterally into the fenestrule, 

 thus imparting to it a slightly sereated. outline. The length of the 

 fenestrule is about one and one-half times the width. "Branches from 

 10 to 13 in a width of 5 mm.; dissepiments 9.3 to 13 in the same length." 



