Mr. Jeffreys on British Mollusca. 31 



of Moller and Morch from Greenland and of Loven from Nor- 

 way, in which nearly all the species (although sometimes dis- 

 guised under different names from ours) are undistinguishable 

 from those of this country, or are at most only local varieties. 

 I have on another occasion pointed out the hindrance caused to 

 science, and especially to Palseontological Geology, by the redu- 

 plication of names for the same species ) and until the errors are 

 rectified and a complete concordance established, it is evident 

 that any catalogues, from which the relative proportions of fossil 

 and recent species are deduced, cannot be of much value. In 

 another respect, too, such catalogues are defective, viz. in as- 

 suming that all the recent species which exist in any given area 

 are not also found in a fossil state. Such is the case with Phi- 

 lippics catalogues (in his work on the Sicilian Testacea and his 

 papers in Wiegmann^s Archives), to which, although accurate to 

 a certain extent, additions are continually being made, so as 

 materially to alter the relative proportions. It is most probable 

 that every species which he has described as now inhabiting the 

 coasts of lower Italy will eventually be discovered to have also 

 had its existence in the Tertiary epoch, and perhaps vice versd. 

 The old adage '^ De non apparentibus et non existentibus eadem 

 est ratio cc surely does not apply to the science of Natural 

 History. 



I will say a few words as to the way in which I believe many 

 exotic species have been introduced into collections and cata- 

 logues of British shells. Whilst enjoying last autumn the 

 hospitality of the Rev. Mr. and Mrs. Collings at the seigneurie 

 in Serk, I witnessed, with a telescope from the tower, a scene 

 which I shall not soon forget. It was that of at least 200 ex- 

 cursionists, who had landed from Guernsey steamers on the 

 little Isle of Herm, and were busily engaged in picking up shells 

 on the famous beach there, — some of them on their hands and 

 knees, others in various recumbent attitudes, and all provided 

 with bags and baskets. I was informed that most of the shells 

 so collected were used in the manufacture of ornamental articles. 

 These collectors were probably careless about the localities 

 whence their specimens were procured ; and thus, from the mix- 

 ture of native shells with others from foreign countries of a more 

 attractive form or colour, has arisen some of the confusion which 

 exists in many collections purporting to be entirely of British 

 species. For instance, in Mr. Macculloch^s cabinet of shells from 

 the Channel Isles, I observed some well-known West Indian 

 species which had been procured in the above manner. Some 

 spurious species have doubtless also been foisted on conchologists 

 by design as well as inadvertence. Maravigna (in his ' Memoires 

 pour servir a PHistoire Naturelle de la Sicile ') states that he had 



