280 {Oct., 1845- 



received its name from its remarkable appearance, arising from its 

 bed being a deposit of a kind of white shell marl. At a short dis- 

 tance it has quite a wintry aspect, the shore appearing as if covered 

 with snow. On near approach, the ordinary observer will be much 

 astonished, and the naturalist much interested in finding a vast 

 quantity of comparatively recent fossil fresh water shells, which not 

 only cover, but in many places appear to form the shore, extending 

 in breadth and depth for several feet. If a bunch of the Helianthe- 

 mum corymbosum, which grows here profusely, be pulled up, 

 nothing but shells and their fragments will be found adhering to its 

 roots. These shells are evidently washed from the deposit of marl 

 in the bed of the pond, as the neighboring inhabitants state that 

 the shores receive an accession of them every spring. 



With the exception of a small species of Cyclas and some frag- 

 ments of Unios, the shells are all univalve, and most of them are of 

 the same genera and species as those found in our fresh water, of 

 the present time, a few being extinct. Many of them have ad- 

 hering to their inside some root-like fibres, which upon examination 

 I find to be a species of Chara. 



It was a matter of much surprise to me that I could not find a 

 single living molluscous animal in the pond, and a neighbor in- 

 formed me " no snails had ever been found, and only a very few 

 muscles with flesh in," in it. 



The pond is in a limestone region ; its water, from its situation, 

 is necessarily calcareous, but probably at some anterior period of 

 time was much more so, was much more affected by the internal 

 temperature of the earth than at the present time, and then teemed 

 with the animals whose testaceous coverings form the deposit of 

 marl. 



It is very evident that the deposit of shell marl belongs to the 

 newer Pliocene of some, or tertiary period of other geologists, from 

 the fact of the existence among the shells of the Limneus Galbanus 

 in considerable numbers, which is an extinct species, the abundance 

 of other species now comparatively rare, and the absence of others 

 now common ; as for instance, the Planorbis trivolvis, our most 

 common species of that genus, is here completely replaced by the 

 P. campanulatus. 



Subjoined is a list of the various fossil shells which I picked up 



