104: Cincinnati Society of J^fatural History. 



about 3-lOths of an inch, though it was probabl}' expanded more at the 

 aperture, which is not preserved in our specimen. 



The description is founded upon a single specimen collected hy Mrs. 

 Warren Shumard, in the upper part of the Cincinnati Group, near 

 Richmond, Indiana, and presented by her to Mrs. M. P. Haines, from 

 whom it was received for definition and illustration. 



MuRCHisoNiA MULTiGRUMA, n. sp. (Plate III., fig. 3; fig. 3«, basal 



view. ) 



[Y.iy.—Multigrumus, much heaped up .] 



Shell medium size or rather large; turbinate above, with about five 

 angular whorls; apical angle from 75 deg. to 80 deg. ; base of the shell 

 very much produced, and forming the wall of the left side of the aper- 

 ture. Body whorl constitutes more than half the shell. 



Surface of the upper whorls apparently smooth — at least no mark- 

 ings have been determined on them; base of the body whorl marked 

 with coarse, backward-curving stria?, which terminate in the columellar 

 lip or wall of the aperture. 



No umbilicus. 



This species is not uncommon in the upper part of the Cincinnati 

 Group, ten miles east of Ma^'sville, Kentuck}^ I collected it, also, at 

 Versailles and Richmond, Indiana, though good specimens are rare. 



It most resembles Safford's M. sinnnerensis, and with the latter, and 

 31. milleri, M. jjei'angulata^ and 31. soroi'cula^ forms a closely-linked 

 group. The whorls in 3f. samnerensis are gently concave on the 

 upper side, and banded below the suture, while in our species, the 

 upper face of the whorls is plane to the suture. The base of the shell 

 in our species is more produced, and the body whorl more strongly 

 marked with backward-curving stria? than Safford's species. 



Ambonychia retrorsa, n. sp. (Plate III., fig. 6. ) 



['Ety. —Betrorstis, turned back.] 



Shell small, equivalve, ver}- convex and rajndly bending from the 

 front backwai'ds. Very high in the umbonal region, and rapidly sloping 

 in all directions, most rapidl}^, however, toward the front. Beaks point- 

 ed, incurved, and rising high above the cardinal margin. Anterior 

 side truncated, and rounding rapidl}^ into the base below; basal margin 

 prolonged and rounded posteriorly; posterior margin moderately con- 

 vex. Hinge line straight, and rapidly descending posteriorly. Surface 

 of each valve ornamented with about fifty-five fine radiating costa\ 



Lengtli of the specimen illustrated, from the points of the beaks, to 

 the most extended part of the basal margin posterioi'ly, about fifty-three 



