62 THE PEOCEEDINGS OF THE LINNEAN SOCIETY 



" Proceedings " of this Society. It was erected originally by 

 Philippi for Lifctorinse with acute whorls, and those peculiarities 

 which have already been referred to. 



It was noticed by M, Crosse, in the Jour, de Conchyl. for 1865, 

 that this diagnosis would hardly warrant a separation from 

 Littorma, but he called attention to another feature that had 

 escaped notice, that is to a basal thickening in a kind of thread 

 about the middle of the aperture. He thought also that there 

 were about nine species. In my paper I attempted to show that 

 there is only one species, and since that time have made a 

 careful comparison of an immense number of individuals from 

 various parts of the coast, and having further observed that all 

 the presumed species breed freely with one another, I make no 

 doubt whatever that this genus, if it is to be preserved, can only 

 be said to be represented by one species.* Now as to the basal 

 funicular thickening we find that it does not hold good for all the 

 individuals. It is present and absent on difiPerent specimens, but 

 more frequently present on old shells. But it has not been 

 remarked that always by the side of it there is a white or yellow 

 spiral line on the outer and anterior angle of the aperture. This 

 white spiral line or groove, for it is both, corresponds with the 

 line I have called attention to in the turbinate Littorince, and I 

 find that it is a groove along which the organs of reproduction 

 are always exserted, whether they be male or female. I have 

 before shown that this ofiice is variously assumed by different 

 shells. It is not easy to explain why this portion of the shell is 

 differently colored, unless it is in keeping with what is noticed in 

 the coloring of certain flowers, butterflies, &c. The whole of the 

 Littorince have the aperture of dark color, though highly 

 enamelled, and this whitish line is a conspicuous diversity on the 

 appearance, though it would be a very narrow view of the 

 operations of nature to say that its only purpose was to attract. 

 Round the mouth of most Bisellce, and close to this spiral line, 



* In the Annals of Nat. Hist, for 1852, vol. II, p. 76, Mr. W. Thompson writes that he 

 had observed several examples of small Littorina rudis in coitu with L. littoralis, and in 

 every instance the male was L. rudis. He suggested that perhaps a hybrid resulted, and 

 this was L. palliata, but that form did not frequent that part of the coast. The question 

 has not, as far as I know, been followed. A few very simple observations in a small 

 aquarium might lead to important discoveries in such matters. 



