638 GEOLOGY OF OHIO. 



Anomalodonta alata, Meek. 



Plate 46, Fig. 1. 



Ambonychia alata, Meek, 1872, Proc. Acad. Nat. Sci., Phila., p. 319; also 1873, Ohio 



Pal., Vol. I, p. 131. 

 Anomalodonta alata, Miller, 1874, Cin. Quart. Jour. Sci., Vol. I, p. 16. 



The interior of the right valve figured on plate 46 was obtained by 

 means of gutta percha from an unusually well-marked cast of the interior. 

 It shows the posterior internal cardinal folds, the large muscular scar, 

 and the pallial line in a very satisfactory manner, and every feature 

 points unmistakably to Anomalodonta. Specifically the form is distin- 

 guished from A. gigantea by the much greater length of the posterior 

 wing, the length of the shell near the dorsal edge equaling or even 

 exceeding the greatest height. Other differences are brought out in a 

 careful comparison of good specimens, but the one mentioned generally 

 suffices in the separation of the two species. In the new species, A. 

 plicata, the width of the shell is less, the posterior margin is not produced 

 above, and the radiating plications are fewer in number and therefore of 

 larger size. 



Formation and locality : Upper beds of the Cincinnati group, at 

 Clarksville, near Morrow, Blanchester, Waynesville and other localities 

 in Ohio; also at Versailles and other localities in Indiana. Prof. Meek 

 gives Cincinnati as the original locality, but I doubt very much that it 

 occurs so low in the series. 



Anomalodonta plicata, n. sp. 



Plate 46, Figs. 2 and 3. 



This species is founded upon a single specimen, a rather well-pre- 

 served cast of the interior of a right valve. Although we have no 

 positive knowledge of the hinge, the downward bend of, and the fold 

 bordering the posterior half of the dorsal edge of the specimen, indicate 

 very strongly the presence in the shell of large internal cardinal folds. 

 The obtusely pointed beak and the depressed space in the cardinal slope 

 also, indeed the whole expression of the cast is so much like that of A, 

 gigantea that I cannot hesitate in referring the species to Anomalodon a. 



The form of the shell is much narrower than in A. alata, the leng h 

 being about 38 mm. and the height 55 mm. These dimensions show it to 

 be relatively also narrower than A. gigantea. But the difference that 

 will distinguish the new form most readily from those species lies in the 

 number and size of the radiating costae. Their exact number cannot be 

 determined from a cast of the interior, they being too obscurely indicated 

 in the cardinal and byssal regions. Still, as the costae are so uniformly 

 distributed over the surface in this and related genera, it is possible to 



