NATUIL\L HISTORY OF ONCHIDIUM 499 
The snails do not emerge to feed when high winds and surf 
are directed against their feeding zones. The tentacles are 
anemotropic organs, which prevent the emergence of the Onchidia 
in such circumstances. 
An analysis has been given of some of the snail's modes of 
response, and of certain general implications of the remarkable 
activities of Onchidium. 
LITERATURE CITED 
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