274 The American Oeologist. May, i89o 
ton, Ky. a, 6 and c three views of the best specimen seen. It is a 
cast of the interior and the largest seen. 
Shells below the medium size, rather convex, elongate, the 
length equalling more than twice the greatest hight. Cardi- 
nal and basal margins nearly straight, subparallel, diverging 
very slightly toward the posterior extremity. Anterior end 
very short, contracted in front of the beaks, narrowly rounded. 
Posterior end not evenly rounded, the curves being a little the 
shortest in the basal half. Beaks small ; umbonal ridge 
scarcely defined, the whole surface of the valves being nearly 
evenly convex, with the point of greatest convexity a little in 
front of the center. The cardinal slope may be somewhat 
flattened. 
Only casts of the interior have been observed. These indi- 
cate that the shell was marked with faint concentric lines of 
growth. The anterior muscular impression is unusually large. 
Length, 25 mm. ; length from beaks to posterior extremity of 
hinge line, 17 mm. ; hight from umbones to basal margin, 10 
mm. ; hight from posterior end of hinge line to basal margin, 
11.5 mm. ; greatest convexity of entire cast, 8 mm. 
This species resembles M. anodontoides Conrad, but differs 
somewhat in outline and in wanting a distinct umbonal ridge. 
Conrad's species evidently belongs to the same section of the 
genus as M.cincinnatiensis H.and W.,in which the shell is very 
thin and the anterior muscular impression faint. 
Position and locality : The types are from the Cincinnati group at 
the hill quarries west of Covington, Ky., and north of Cincinnati, 
Ohio. The horizon is from 300 to 350 ft. above low water mark in the 
Ohio river. I have casts also of the same or of a similar species from 
an horizon about 200 ft. lower in the series. 
Modiolopsis milleri, n, sp. 
Fig. 3. Modiolopsis miUeri, n. sp., Cincinnati group, Cincinnati, 
Ohio, a, a large specimen preserving the shell, b and c, cardinal and 
