526 Misses M. D. Haviland and F. Pitt on the 
Certainly thrushes seem to destroy plenty of Helix aspersa, 
whose shell appears to be more inconspicuously coloured 
than that of H. nemoralis. 
Mr. 'Trueman’s tables do not give an exact idea of the 
‘** conspicuousness ”’ of a given shell. For instance, a “ two- 
banded” specimen might answer to the formula (123)(45) 
and appear nearly black; or it might be described as 00230 
and look almost yellow. This would make all the difference 
to its conspicuousness. But the figures given are certainly 
curious, and two explanations suggest themselves :— 
(a) The possibility admitted by Mr. Trueman himself in 
his last paragraph, when he says: “ The figures 
appear to show that banded shells are less liable 
to be seen—or, at least, to be eaten.’ The italics 
are mine. 
(6) That the darker varieties predominate in bushy 
places and the lighter in the open, where the 
thrushes generally feed. Hence the birds would 
find a larger proportion of unbanded shells. 
With these ideas in view I made two series of observations 
in the summer of 1917; I had hoped to continue them in 
1918, but circumstances prevented this, and unfortunately 
neither of them are as complete as they should be. 
The first experiments were made on Maidenhead Thicket, 
in an open grassy place surrounded by bushes, between 
June 25th and July 2nd. The snails were tethered to pegs 
by black threads, varying from 6 to 12 feet in length, passed 
through a hole drilled in the lip of the shell, and the numbers 
were checked every evening. Snails disappeared on the 
second and succeeding days, but I did not obtain positive 
proof that they were taken by thrushes until June 30th. I 
found a four-banded shell, still fastened to its thread but 
unmistakably smashed by a thrush, and some yards away 
was a second four-banded shell, also broken, beside a stone. 
On the following day, in addition to two three-banded shells 
which had been carried off altogether, I found three four- 
banded shells which, with the threads still attached, were 
lying each beside a stone with the shell smashed, but with 
the animal uneaten. 
For convenience in working, the snails, whose tethering 
threads became much entangled, were put out in five groups 
—A, B,C, D, E. Each group consisted of from four to six 
snails tied to one peg and selected quite haphazard. The 
groups were all within an area of 25 yards, but A and B 
were much overhung by bushes, C was a little more exposed, 
and D and E were quite in the open. Four snails were 
