Dr. Gregory is such a good observer that we can only accept the facts he gives, but at the same time I have never noticed the correspondence myself when collecting butterflies either in the Malay Peninsula or in South Africa. There is probably here a partial but not absolute rule in the appearance of these insects, and, though I cannot support it from my own experience, it would be most interesting and valuable to obtain the observations and opinions of other tropical field entomologists.
Lord Walsingham in 1885 advocated parallel views on "some probable causes of a tendency to melanic variation in Lepidoptera in high latitudes." In discussing the probable explanation of the white covering of many arctic and alpine mammals and birds, and the dark hue of many lepidopteral species in the same habitats, he accepted the views which were at least enunciated by Craven in 1846 as explanatory of the first phenomenon, which accounts for the same by the well-known fact of white being a bad radiator of solar energy, and white-covered animals thus being able to retain their heat to the greatest advantage. The dark insects, on the contrary, are considered to have their advantage in being better able to absorb the solar radiation.—Ed.
MOLLUSCA.
Distribution of Worm-eating Slugs.—As there appeared in the November number of 'The Zoologist' a note regarding the distribution of worm-eating Slugs (Testacellæ), it might be interesting to record that these animals are found here, often in considerable numbers. I might mention that here they are chiefly found in the gardens near the sea.—Alec Goldney Headley (Portchester, Hants).
