Selection of Helix nemoralis by the Song-Thrush. 529 
Tas.e III. 
Control Collection for comparison with Table II. 
Formula, Number. Per cent. of total. 
LIDS YG) ON a See ee Re 8 13'5 
TS (C5) oS Renee Sele 3 5-0 
CEC a ere eee 1 1:7 
OUSAOE critiete wile /elcic-cl a. sivie@ 1 EF, 
Py ites Woks wake adh 1 ECE 
BOO ee acreesctaaheal ietoacte it 17 
OOS OO oi ere eran os cts chlo ake leven 1 ez 
00000 (Jibellula)®........00.. 4| “eh 
Vars. rubella and castanea .... 6 | 
TU CHTUNGIUG wis ti o'a afetehotareite ries 33 55°9 
Motall-. tes, cise cishetace oes 59 
Section II. By Frances Pitt. 
At the request of Miss M. D. Haviland, I obtained a 
young song-thrush in the spring of 1918, and reared it by 
hand, in order to ascertain whether the thrush has a 
preference for a particular variety of Helix nemoralis, and 
also if the habit peculiar to the thrush of breaking snail- 
shells on an “anvil” is instinctive or acquired through 
experience by each young bird. 
When the bird was fully fledged I offered it two examples 
of Helix nemoralis, of formule 00000 and 12345 respec- 
tively. The thrush paid no attention to them unless they 
moved, and then it pecked at the protruding tentacles until 
the snails withdrew into the shells, after which the bird 
ignored them. 
The experiment was repeated the next day, with the same 
result, except that the bird pecked the shells sharply two or 
three times. 
On the third day four snails were offered—two 12345 and 
two 00000. This time, when the bird’s attack caused the 
snail to retract, the thrush turned one shell over, looked 
into the cavity, and shook it vigorously before casting it 
aside. 
At the fourth trial, two days later, five nemoralis were 
offered—two 00000 and three 12345. This time the thrush 
carried one of the former variety round the cage, and struck 
it on the ground until it fell from his grasp, whereupon he 
picked it up again and battered it on astone. As it did not 
crack readily, he seized each of the others in turn, and tried 
in vain to break them. Finally, he took the first snail 
again, and ultimately broke it open and ate it. 
From the foregoing observations I am inclined to believe 
that the only part of the snail-cracking habit which is 
