JONES : MOLLUSCAN ALBINISM. 7 
from a bank in Derbyshire large numbers of Helix concinna 
var. albida. ‘This year, I took at Disley in Cheshire specimens 
of Hyalinia cellaria and 7. alltaria, both white, and both from 
the same bank, and that not thirty feet long. Again, in the 
same locality last year I found in a pile of bricks, not ten feet 
square, two specimens of Hyalinza cellaria var. albina, and some 
type individuals, the shells of which were so light in colour that 
it was difficult to say whether they were albinos or not. Indeed, 
though it sounds anomalous to say so, a Hyalinia to be white 
must have a shade of green. This green appearance is, how- 
ever, I am of opinion, due more to the composition of the shell 
than its colouring matter. 
There are many more instances of gregarious habits among 
molluscan albinos, so called, but one will suffice. Captain 
Farrer has lately taken at Bassenthwaite, Pupa cylindracea var. 
albina, in considerable quantity. There is a curious point with 
regard to this particular colony. The mollusca occur upon a 
wall, which is whitewashed in one part; on that part which is 
whitewashed, and that only, occur the animals with the white 
shells, though the type is plentiful on that portion of the wall 
which is not whitewashed. Captain Farrer is inclined to regard 
this instance as one of protective colouring. I cannot altogether 
agree with him. I think the dark body of the mollusc, being 
very plainly visible through its semi-transparent shell, prohibits 
the idea that that shell is of much service as a protective agent. 
All these facts, I believe, go to prove that albinism amongst 
mollusca is extremely hereditary. Take the case of Planorbis 
corneus at Birch. Mr. Standen can remember a few years ago 
when, out of several hundreds, he did not obtain a single white 
specimen. Then a few began to appear, and, in succeeding 
years, the few continually increased, till in 1893 they formed nearly 
three-fourths of the total. Probably in this case a few albinos, 
or perhaps a brood of albinos, were produced accidentally, so to 
speak, and these growing up and coming to maturity have 
propagated the abnormality, some doubtless, however, reverting 
