280 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 
second edition be useful—as the first has been and 
still is—for ascertaining the number of species and 
their local habitats; but it will also be of great 
value for showing how much our knowledge, 
especially of the local and general distribution of 
species belonging to the different groups, has been 
increased within a definite period. 
Having devoted part of my leisure, during the © 
past year or two, to the working out of the distri- 
bution of the Land and Fresh-water Mollusca about 
Greenock, as well as in a few places beyond but 
within easy access of that town, perhaps the result. 
of these researches, embodied in the following Notes 
and List, may form a contribution—though possibly 
not a very important one—to the second edition of 
the Fauna and Flora referred to. 
Those who are studying this group of the Mollusca | 
will doubtless have noticed a growing tendency 
among conchologists to be more and more discriminat- 
ing. Differences in banding and coloration, as well 
as in form, which used to be only incidentally referred 
to in the description of the species, are being more 
and more separated and raised to varietal or sub- 
varietal rank; and considering the exceeding vari- 
ableness of many species, it becomes to some extent 
interesting to note the number and distribution of 
the different varieties. This critical study of the 
variations in different species may, if judiciously 
carried out, be of considerable importance in increas- 
ing our knowledge of the relationship of species; 
but whether the variation in the colour and number 
of bands of the shells of such species as Helix — 
nemoralis and H. hortensis deserves all the attention 
it is receiving, I will not venture to say. I think, 
however, that these variations may be regarded as 
at least worthy of some study by those who have 
time to devote to it. The local distribution of some 
of these colour-varieties is rather interesting. By 
the side of the branch line connecting the ae 
in Shielhill Glen with the Wemyss Bay Railway, I 
