UNDER the above heading, in your issue of April 1, Mr. J. T. Gulick has an interesting communication, in which he asks whether it is possible to explain right-handedness, the dextral or sinistral coil of snail-shells, and similar features, as having any utility to the species of which they are certainly characteristic. Can it be due to natural selection that one snail is dextral, while another is sinistral?