Cincinnatian and Lexington Fossils 39 



convex. The concavity of the cardinal slopes suggests that the 

 beak was formerly distinctly elevated above the plane of the lower 

 valve. The radiate lines of minute pits are separated by relatively 

 wide, flat interspaces. The foraminal depression was 2.5 mm. 

 long in a specimen having a length of 17 mm., but 24 mm. is 

 mentioned as the average length of the shell, (plate v, figs. 3, 4.), 



The specimen from which figure 8 on plate i, of vol. 2 of the 

 beak and along the margin of the shell almost as far as the anterior 

 Ohio Paleontology was prepared is preserved in the American 

 Museum of Natural History, in New York City. It is numbered 

 1335-2, and was identified by Hall and Whitfield provisionally 

 wi:h Trematic punctostriata. The punctae are very minute and can 

 be recognized only under a lens. The punctae are distinct at the 

 edge, but are absent from the greater part of the shell, forming 

 the central and surrounding parts of the valve. Compared with 

 the figure in the Ohio Paleontology, the rows of punctae are closer 

 together, and the anterior outline of the shell is more rounded, and 

 not straightened as figured, although wider than long. This speci- 

 men was referred by Ulrich to his Treniatis oblata, in his original 

 description of that species, possibly on the basis of the illustration 

 in the Ohio Paleontology. 



The specimen from which figure 9 on plate i of vol. 2 of the 

 OJiio Paleontology was prepared and here illustrated by fig. 2 on 

 plate v, forms No. 102 of the James Collection, at Chicago Univer- 

 sity. Its length is 15 mm. and its width is 15.2 mm. The fora- 

 minal depression is almost 3 mm. in length, and is V-shaped in 

 form at its origin. The concentric striations are faint. The piis 

 are minute, and are arranged in rows separated by relatively wide 

 interspaces. They are restricted to the area posterior to a line run- 

 ning transversely across the shell at the anterior end of the pedicel 

 notch. This specimen is regarded as belonging to Treniatis 

 fragilis, although it is not known from what horizon it was ob- 

 tained. 



Possibly the specimen represented by figure 8 in the Ohio 

 Paleontology, described above, also may belong to Treniatis fra- 

 gilis. In Treniatis oblata the pits become larger anteriorly, along 

 the margin, and approach each other sufliciently to form a net- 

 work; moreover, the shell has a distinctly ovate outline, the sides 

 rounding rather abruptly into the anterior outline of the shell, 

 which is distinctly less convex or even nearly straight. 



