14 



Now, tliat this may be correctly understood, I must state, that irt 

 the above description Deshayes speaks of the apex of the shell as the 

 summit, and of the anterior, wider part as the base, though he places 

 his figure exactly in the reverse position, putting the anterior wider 

 part upwards, and the apex downwards ; and, moreover, that the ex- 

 pressions " audessous'' and " audessus" in the above description are to 

 be taken in reference to the position in which the figures are placed in 

 his plate, and not with reference to what he has called summit and base 

 in his description. 



Taking the above description alone, and without further reference to 

 the figures than is necessary to understand it correctly, there is nothing 

 in it to lead any one to suppose that Deshayes is describing a different 

 thing from Defrance, and the conclusion must be drawn, that his 

 Melania inquinata is identical with Defrance's and Sowerby's : but any 

 one would be led greatly to doubt the identity of the species who placed 

 any dependence upon the figures in Deshayes, which are very little like 

 the shell represented in Mineral Conchology, and not much more like 

 five authentic specimens at present in my possession, which represent 

 two of the varieties from different localities in France ; indeed, these 

 figures of Deshayes are such, that I think it would scarcely be possible to 

 identify the fossil by them alone, and without the aid of other figures 

 and descriptions. The second result of this examination is, nevertheless, 

 that Deshayes' fossil Melania inquinata is identical with Defrance's, and 

 that they are represented in this country by the shell named Cerithium 

 melanioides in Mineral Conchology ; afterwards altered in the Index to 

 the sanie work, to Potamides politus (melanioides) but which, con- 

 sequently ought to bear the name of Melania inquinata of Defrance. 



I must now institute a comparison of this fossil species with the 

 recent one, which Deshayes asserts to be identical with it. For this pur- 

 pose I refer to the Mag. de Conchyliologie, page and plate 1 3, and I 

 transcribe word for word his statement relative to it. 



" M. souiLLEE. M. inquinata, Defrance. Deshayes. 

 Testa transverse multistriata, apice costata ; costis longitudinalibus ; 

 stria unica. superiore nodulosa. 



