NOTE. 
Not having had the advantage of examining M. De- 
shayes’s admirable work on the fossil shells of the Paris 
basin, until after a part of the foregoing descriptions were 
printed off, it has, necessarily, been out of my power to 
make any comparisons with his species. The following 
seem important enough to be introduced here. 
Pasithea umbilicata (nobis), page 103, resembles M. De- 
shayes’s figure (Coquilles Fossiles, pl. 9, figs. 1 and 2,) 
of Lamarck’s Bulimus terebellatus. 
All the species figured by M. Deshayes as Melanie, in 
pl. 13, vol. 2d., and part of those of pl. 14, belong to the 
genus Pasithea (nobis). It must be evident, to every geolo- 
gist, that the division of fresh water and marine shells, is all 
important, involving facts of the highest interest, as re- 
gards alternate strata, such as exist in the Paris basin. 
If we do not make the breathing of salt and fresh water a 
sufficient character, as well as that of breathing air, for 
generic distinction, we cut ourselves off from the use of a 
most valuable characteristic, to designate the strata of 
groups, see p. 99. 
Venericardia rotundata (nobis), resembles V. squamosa, 
of Lamarck, as figured by M. Deshayes, pl. 26, figs. 9 
and 11. 
