232 



NEW FOSSIL SHELLS 



Genera. 

 Marginella, 

 Melongena, 

 Mitra, 

 Modiola, 

 Monodonta, 

 Monoceros, 

 Monoptygma, 

 Murex, . 

 Mya, . 

 Myoparo, 

 Mysia, 

 Mytilus, . 



Nassa, 

 Natica, . 

 Nautilus, 

 Nucula, . 

 Nummulites, 



Oliva, '. 

 Orbicula, . 

 Orbis, 

 Ostrea, 



Pandora,' 

 Panopsea, . 

 Pasithea, 



No. of species. 



. 5 

 . . 5 



2 

 . . 18 



2 

 . . 2 



1 

 . . 1 



1 



. . 9 



. 8 



. . 4 



. 1 

 1 



. 16 



. . 3 



. 5 



. . 20 



. 2 



. . 7 

 1 



. . 11 

 1 



. . 12 

 1 



It is to the kindness of Mr. Tuomey, of Petersburg, that I owe the following shells, 

 as well as those in the list a few pages back. Most of the smaller species herein 

 described, I met with by carefully examining the sand scraped from the cavities of larger 

 shells, as well as a small portion of the marl of the vicinity, with which Mr. Tuomey was 

 kind enough to favor me. I mention this merely to show the importance of thoroughly 

 searching the strata of the various localities before we conclude that we have all the 

 species existing there. Attracted by the beauty of the larger shells, conchologists have 

 very much neglected the more minute ones, which require a closer examination, and 

 thus our knowledge of our fossil conchology is still limited. I may as well observe here, 

 that I found the species met with in the sand from the cavities of the larger shells, in 

 general, different from those in the loose marl. It is difficult to give a reason for this, 

 unless there were species which usually inhabited the interior of dead shells, like the 

 recent Valvata tricarinata, Say. 



In looking over these shells, I have been struck with the general resemblance which 

 obtains between them and those of a corresponding age from Dax. This is peculiarly 

 observable in the genera Acteon, Pasithea, &c. which are very numerous in both 

 localities. Their connexion is so close that in some cases they are scarce specifically 

 distinct. 



