Cincinnati Society of Natural History. 



localities are in Mr. Miller's collection, as well as in Mr. 

 Faber's collection. When Palceoconcha faberi was defined, it 

 was distinguished from obiiqua by its greater proportional 

 height, by the prolonged beaks projecting high above the 

 hinge-line, the less oblique form, and generally larger size. 

 Xo one having any knowledge of shells ever supposed the 

 two species are identical, and the question presented was 

 whether or not they could be congeneric. The reader must 

 bear in mind that all the specimens belonging to these species 

 then known were casts, and no part of the shell had ever 

 been found. The number of specimens of Palceoconcha faberi 

 in the two collections number several hundred, and each of 

 them was carefully and thoroughly examined by each of the 

 authors, with the aid of good magnifiers, and not a vestige of 

 evidence of a crenulated or denticulated hinge was discovered 

 or can be discovered in any specimen belonging to either 

 collection. The form of PalceoconcJia faberi precludes the 

 probability, if not the possibility, that it can belong to the 

 genus Tellinomya, for no one can conceive of a shell having 

 a cast with such long, close, sharp-pointed beaks, opening on 

 the wide, denticulated hinge of a Tellinomya. The evidence 

 thus far adduced amounts to this, that the form of obiiqua is 

 not inconsistent with a Tellinomya. but there has been no 

 evidence discovered to show that it is a Tellinomya ; while 

 the form of a faberi shows it can not be a Tellinomya , and 

 there is no evidence to prove that it can belong in the same 

 family with Tellinomya. But there is further negative evi- 

 dence on the subject, which we will now proceed to present. 



The species of Tellinomya , which occur in the Hudson 

 River Group, in Indiana and Ohio, have thicker shells, in 

 proportion to their size, than belong to any other genus of 

 the Lamellibranchiata found within the Group, and the shells 

 are more abundant in proportion to the number of casts than 

 the\* are in any other genus. The denticulated hinge lines of 

 each species are common wherever the species occurs. We 

 find the denticulated hinge lines of Tellinomya levata and T. 

 pectunculoides as frequently as we find a good shell or a good cast 

 of either one, though neither species is common. The cast of 

 Tellinomya levata var. occidentalis of Meek has never been 

 found, though not less than fifty specimens with the shell on 



