6S6 GEOLOGY OF OHIO. 



than was the original placement. The shell is more elongate than any 

 of the other species now referred to Tec hnop horns, while the clavical is 

 not only longer and more slender, but much more oblique as well. 



For?nation and Locality: Lower beds of the Cincinnati group, Cov- 

 ington, Kentucky. 



Family CYCLOCONCHIM, Ulrich. 



Genus CYCIyOCONCHA, Miller. 



Anodonlopsis, Meek, 1871, Amer. Jour. Sci. and Arts, 3d ser., vol. ii, p. 297; 1873, 



Pal. Ohio, vol. i, p. 140. (Not Anodontopsis of McCoy.) 

 Cycloconcha, S. A. Miller, 1874, Cin. Quart. Jour. Sci., vol. i, p. 231. 



Shells rather small, rounded or ovate, subequilateral; valves equal, 

 moderately convex, with small beaks and no umbonal ridge. Surface 

 marked with very fine concentric lines and occasionally with obscure 

 rays on the post-cardinal slope. External ligament occupying a narrow 

 groove extending both anterior and posterior to the beaks. Hinge with 

 one strongly defined, snbtriangular cardinal tooth beneath the beak of 

 the right valve, with a small pit just in front of it and a corresponding 

 large pit and a small tooth in the left valve. Posterior lateral teeth long 

 two in the left valve and one, two or three in the right. Anterior lateral 

 teeth similar to the posterior laterals only shorter. The large cardinal 

 tooth (in the right valve) is usually divided into three radially disposed 

 portions. Pallial line simple, muscular impressions well defined though 

 not deep, the posterior slightly the larger, both with a small pedal muscle 

 scar above and occupying the small spaces left between the adductor scars 

 and the opposite extremities of the two sets of lateral teeth. 



r 



Type : Cycloconcha mediocardinalis , S. A. Miller. 



Plate 51, Figs. 14-21. 



I have not the slightest doubt of the generic identity of Dr Miller's 

 type and the shell named Anodontopsis? milleri by Prof. Meek, and the 

 one next described as a new species under the name of Cycloconcha ovata. 

 I have given figures of the exterior and interior of these three species 

 on plates 48 and 51, and am confident that no one can compare them 

 without coming to the conclusion that the}' are congeneric. I will ad- 

 mit that while there are really three lateral teeth on each side in the 

 right valves of C mediocardinalis and C. ovata there is but one that 

 strictly speaking ma)' be called a tooth in C. milleri. Still, and this part 

 was noticed also by Meek, the other two laterals are represented in that 

 species in a rudimentary condition, there being a faintly raised line on 

 the outer sides of the two furrows which received the two laterals of the 

 left valve. 



Meek's description of. Anodontopsis? milleri,. ox Cycloconcha milleri, 

 is it should now be called, is full and correct in all respects except when 



