It has been shown (Arnold, 1957) that when exposed to air the common British limpet, Patella vulgata L., reacts to splashing with normal or moderately diluted sea water by raising the front edge of the shell, and that the amount of this movement can be correlated with the degree of dilution and with the tide level from which the animals are obtained. A basically similar result was obtained by the use of solutions of sodium chloride. The precise factors influencing the limpets were not identified. Additional data can now be presented on these and other reactions of P. vulgata as a contribution towards further definition of these factors.