304 NATURAL HISTORY BULLETIN. 



species are identical with Testacea, now inhabiting the same 

 part of the U. S. 11 The species of Helix, Helieina, Pupa and 

 Succinea are, however, in no sense aquatic, and it will be ob- 

 e A that the deposit from which the shells of the species 

 belonging to the aquatic genera Limmca, Planorbis, Physa 

 and Cyclas (SphtBrium or Pisidium) were obtained is very 

 doubtfully loess. — certainly not typical loess. Finally, in the 

 Principles of Geology" Lyell says that this loess is "full of 

 land-shells such as Helix and Pupa, together with the amphib- 

 ious genus Succinea, all of species now living in the same 

 try. At a few points in the lower part of this formation, 

 I observed shells of living species of Lymnea, Planorbis and 

 Cyclas, — genera which inhabit ponds. . . . The only fossils 

 of a truly fluviatile character, which have been met with any- 

 where in this loess are the remains of three fish discovered 

 lately (March ic 1 ">y Colonel Green. They were found 



in the great platform of loess, two miles north of Vicksburg, 

 and only four feet below the surface, at the height of 200 feet 

 above highwater mark.' 1 



The genus Succinea cannot be properly designated as am- 

 phibious. It consists of two very distinct groups of species, 

 to only one of which, represented by the species rc/itsa 

 the term may be applied, and this one is not 

 represented in the southern loess, and but very sparingly 

 in that of the north. The common and characteristic species 

 of the 1 only at Natchez but in all the Mississippi 



valley, belong to the other section of the genus, of which 

 S. cb/iuua, S. grosvenorii and S. avara are members, and all 

 of these are upland species, or at least are commonly found on 

 higher grounds, — and none of them are in the remotest sense 

 aquatic or u semi-aquatic. v Viewed in the light of the quota- 

 tion from the London Times, the deposit in which the pond 

 snails were obtained can scarcely be referred to as typical loess. 

 The occurrence of the fish-bones is unique and throws no light 

 on the prevaili ; g loess conditions. Such limited quantities 



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