ORISKANY SANDSTONE. 
149 
3. Atrypa peculiaris (Annual Report of 1841, p. 56.) Lower valve flat, concave towards 
the base with the margins elevated, the front extending into a linguiform projection ; superior 
valve convex, front margin folding over the edge of the lower, and joining by a few seme or 
teeth. 
This shell is known by its peculiar projection in front, the strong depression in the lower 
valve toward the margin, and the folding down of the edges of the upper valve. 
The fossils here figured are perfect, the shell remaining entire. Casts of these, however, 
are the more usual forms seen. In the following woodcut two of these casts are represented : 
60 
4. Cas; of Atrypa unguiformia. 5. Cast of Deltliyris arenoaa. 
4. Atrypa unguiformis, Conrad. (Hipparionix proximus, Vanuxem, Final Geol. Report, 
p. 124, fig. 4.) This fossil, usually found as a cast, so much resembles the impression of a 
horse’s hoof, that it has for a long time maintained the name, and even by well-informed per¬ 
sons it was considered as the impression of the hoof of some animal. 
This is one of the common forms in the rock, and will be readily recognized. 
5. Deltliyris arenosa, ut supra. This is the usual appearance of the cast; it is distin¬ 
guished by its projecting beak, which is often broken off much shorter than here represented. 
In addition to the fossils here figured, there are numerous other forms which are almost 
equally abundant. At Vienna, Ontario county, I obtained a species of Ichthyodorulite about 
four inches long ; the specimen however is too imperfect to represent in a figure. Several 
others were seen in some blocks of stone from the same place, which were used in the glass 
factory at Clyde. These however were partially dissolved by the percolation of water through 
