82 ( PALEONTOLOGY OF OHIO. 



generally smooth and destitute of markings of any kind. The species 

 is readily distinguished from the other forms associated with it hy the 

 more circular form, T. levata and Lyrodesnha Cincinnatiensis, both being 

 more pointed posteriorly and angular along the umbonal ridge. 



Formation and locality: In the Hudson River group, at Cincinnati, Ohio. The 

 original specimens were from the cabinet of Mr. C. B. Dyer. 



TeLLINOMYA lev ATA. 

 Plate 1, fig. 23. 



HTueida levata, Hall ; Pal. N. Y., "Vol. I., p. 150, pi. 34, fig. 1. 



TeUinomya levata, Hall; Descr. New Species of Fossils from the Hudson Eiver Group, 



etc., 1871 ; Expl. of pi. 3, fig. 27. 

 TeUinomya levata, Hall ; 24th Kept. State Cab. ; Expl. of pi. 7, fig. 27. 



The specimens of this species which we have observed from Ohio 

 localities have usually been in a very bad state of preservation, seldom 

 retaining the general features of the shell sufBciently perfect for identi- 

 fication. The species found in New York is sub-rhomboidal in outline, 

 broadly sub-ovate, obtusely pointed at the posterior end, and rounded 

 anteriorly, with ventricose valves and proportionally large, pointed, 

 moderately incurved beaks. The specimens are usually about half an 

 inch long, and a little less in height. The individual figured shows only 

 the hinge plate and a portion of the margin of the shell, the interior 

 being filled with rocky material. The species may be readily distin- 

 guished from other similar forms associated with it by the curvature of 

 the hinge^ plate beneath and posterior to the beaks. 



Formation and locality: On the surface of the limestone slabs from the Hudson 

 Elver group, at Cincinnati, Ohio, and also occasionally flattened individuals from the 

 •softer portions of the group in the same vicinity. 



Genus LTRODESMA, Conrad. 

 Lyeodesma Cincinnatiensis. 



Plate 1, fig. 25. 



Lyrodemia Cincinnatknik, Hall ; Descr. New Species of Fossils from the Hudson River 



Group, etc., 1871, p. 4. 

 I/yrodeama Cincinnatiensis, Hall ; 24th Eept. State Cab., p. 227, pi. 7, fig. 28. 



" Shell small, sub-rhomboidal in outline, and obtusely pointed at the 

 postero-basal angle ; valves moderately convex, with a sub-angular um- 



