156 POTTSVILLE FAUNA OF OHIO 



Class Echinoidea 

 Genus Archaeocidaris McCoy 



Archaeocidaris spines 

 PI. VI, figs. 14, 15 



Description. Spines of an unknown species of Archaeocidaris are 

 present in the Lower and Upper Mercer members, but are particularly 

 common in the Lower Mercer limestone of Scioto County. All the 

 specimens examined are imperfect, the longest fragment measuring 

 about 6 cm. and having a diameter of 4.5 mm. The spines are very 

 slender and, judging from their very gradual taper, must have been at 

 least from 12 to 15 cm. in length. The surface is ornamented by four 

 vertical rows of stout spinules about 2 mm. in length and about 4 to 6 

 mm. apart in a vertical direction; the spinules of the vertical rows 

 alternate irregularly with each other. The basal ring and other char- 

 acters of the spine are unknown. 



Horizon and locality. Lower Mercer limestone: Scioto County, 

 Vernon Township, Locality 31, c; Perry County, Somerset, Locality 

 35, c. Upper Mercer member: Scioto County, Bloom Township, 

 Locality 59, r. 



PHYLUM VERMES 

 Class Chaetopoda 



Genus Spirorbis Daudin 



/ 



Spirorbis sp. 



Description. Several specimens belonging to this genus, measuring 

 about .5 mm. in diameter, have been found adhering to other shells in 

 the Black Flint member. Specific determination, however, is impos- 

 sible from .the imperfect condition of the material. 



Horizon and locality. Black Flint member: Vinton County, Lo- 

 calities 91, 92, r. 



PHYLUM MOLLUSCOIDEA 



Class Bryozoa 

 Genus Bascomella n. gen. 



Description. A parasitic, boring bryozoan which has been assigned 

 to the family Rhopalonariidae of the Order Ctenostomata. Zoarium 



