324 SCHARFF : SHELLS FROM THE ALLUVIUM. 



small Vertigines , as well as those living in freshwater like a few of the 

 Fianorbes, Bithynia tentamlata^ &c., occur in great quantities in 

 the alluvium, whilst those which frequent higher regions are either 

 scarce or absent. 



It was in March and April this year when I first went out 

 collecting the alluvium, and whilst separating the various species 

 into different boxes, I looked out in vain for the very rare Acme 

 Simoniana, which the distinguished conchologist Mr. Gassies of 

 Bordeaux discovered in the alluvium of May 1856. 



This diminutive shell was first classed among the Paludince 

 by Moquin-Tandon, but after another careful examination of the 

 shell the same author published it afterwards in his " Natural His- 

 tory of terrestrial and fluviatile molluscs of France " under the 

 Acme. It has never been met with alive, so as to allow the 

 structure of the animal to be studied. 



The catalogue of the fauna of the department " la Gironde " 

 by Gassies, published in 1859, comprising the district round about 

 Bordeaux, enumerates 138 species. 



In the book entitled the " fauna of the county of Nassau " by 

 Dr. Kobelt, the author describes the shells he found in the neigh- 

 bourhood of Frankfort in Germany. The total number of species 

 amounts to 140, about 120 occurring in the immediate environs 

 of the town, out of which he mentions 47 as occurring in the 

 alluvium of the river Maine. 



The alluvium of Bordeaux i.e. of the river Garonne yielded to 

 me 60 species, amongst which one proved to be new to France and 

 besides that there was an undescribed variety of a Pupa. 



It is a very singular fact that the quantities of species taken 

 in the alluvium of the two rivers Maine and Garonne nearly agree 

 with one another as you will see by the following numbers : — 



Alluvium of river Maine contained 47 species out of the 

 1 20 living in the environs or 0.39. 



J.C.,ii., Nov., 1879 



