MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
77 
are not so strongly marked on other specimens as on the single 
one at hand which shows the surface features. 
Locality and formation.^ — Quarry J mile northeast of Center- 
ville, Ohio; in the argillaceous strata immediately beneath the 
Brassfield limestone. 
Remarks.^ — These Centerville specimens bear some resemblance 
to Whitfieldella ovoides Savage, from the Edgewood limestone of 
Illinois and Missouri and the Channahon limestone of Illinois. 
Better specimens are needed to make strict comparison possible. 
A similar form, 13 mm. in length, was found by Professor W. 
H. Shideler about 4 feet below the base of the typical Belfast 
bed exposed 2 miles south of West Union, on the Beasley Fork 
road, in strata containing Hormotoma sp., and Rhynchotreta 
thebesensis. 
Rhynchotreta thebesensis Foerste 
Plate XIV, fig. 15 
Rhynchotreta thebesensis Foerste, Bull. Sci. Lab. Denison 
Univ., 14, 1909, p. 94, pi. 4, figs. 66 A-C; Savage, Bull. Geol. 
Surv. Illinois, 23, 1913, p. 80, pi. 4, figs. 19-20. 
Valve, regarded as brachial, 16 mm. long, 16 mm. wide, with 
a convexity of 4 mm. Ornamented by 10 coarse, radiating 
plications which at the anterior margin of the shell are strongly 
angular and 1 mm. in height. In the absence of the pedicel 
valve, and without any knowledge as to the structure of the 
inner surface of the valve at hand, it is impossible to determine 
with confidence the generic relations of this valve; but, in its 
size and general appearance, it resembles the shell described from 
the Edgewood formation of southern Illinois, and eastern 
Missouri, under the name Rhynchotreta thebesensis. 
Locality and formation.^ — Found by Professor W. H. Shideler 
on the E. P. Smalley farm, 2 miles south of Lawshe, on a small 
creek flowing into Brush creek from the east. A similar speci- 
men was found by him also two miles south of West Union, 
along the Beasley Fork road, beneath a typical exposure of Bel- 
fast rock about 4 feet. The Belfast bed here is 1 foot thick. 
