316 Cincinnati Society of Natural History. 



be considered as an inorganic substance on account of its peculiar 

 torm and the number of specimens discovered. If it is organic, it is 

 certamh^ an anomal3^ I have had the specimen in mj^ possession for 

 the past two j^ears, without any determination of its character, and I 

 now illustrate it, hoping that some one may suggest its true relations 

 or affinity. 



CUNEAMYA PARVA, n. Sp. 

 Plate Vlir.. fig. 5, view of the right valve; fig. oa, cardinal view of the same specimen. 



Shell small, equi valve, dorsal view sub-elliptical in outline, side view 

 half cordiform, much the largest anteriorlj^, and cuneiform from the 

 anterior third to the posterior end. Valves ventricose in the umbonal 

 region, the umbonal ridge extending along the middle of the shell until 

 it fades away at the posterior end. Beaks proportionall}^ large, and 

 projecting over the cardinal line until they come in contact near the 

 anterior end of the shell. Anterior end rounding from the lunule into 

 the base. (The illustration is not exactly correct in this respect.) 

 Cardinal margin straight from the beaks posteriorly about two thirds 

 of the distance to the posterior end, and sub-parallel with the base ; 

 the valves are so inflected as to form a narrow false area or escutcheon 

 behind the beaks. Surface ornamented by concentric striae, which 

 commence at the inflection of the lunule, and sweeping around the um- 

 bonal ridge, bend forward and terminate at the elevated cardinal 

 margin or rim of the false area or escutcheon. 



Length of a specimen, 55-100 inch ; height, 22-100 inch, thickness, 

 28-100 inch. 



This specimen is in my collection, and was found in the lower part 

 of the Hudson River Group, at Cincinnati, Ohio. 



OrTHODESMA OCCIDENTALE, U. Sp. 

 Plate VIII., fig. 6. view of the right valve : fig. 6a, dorsal vieAV of a cast. 



Shell very small and thin, cardinal and basal margins sub-parallel ; 

 hinge line straight, posterior to the beaks, and about three-fourths the 

 length of the shell; anterior end declining forward from the beaks to a 

 point, and then rounding off into the base ; posterior end rounded ; 

 beaks extending above the hinge line ; umbones flattened, and sending 

 an angular ridge forward to the base, and a rounded swelling posterior- 

 ly, which fades away toward the basal extremity. 



Surface marked b}^ strong concentric lines, or imbricating m'arks of 

 growth which are distinctl}' retained on the casts. The illustration, 



