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Show 1903.] ON COLOUR-HEREDITY IN FANCY MICE AND RATS. 71 Only a single specimen was obtained by Mr. Robert. It agrees exactly with the figs. 14 and 15 above cited, the shell there depicted also having been collected at Corumba. On comparing this specimen with d'Orbigny's types, I have come to the conclusion, in agreement with Mr. Pilsbry, that the change of name proposed by M. Ancey for this shell was not necessary. BULIMULUS CORUMBAENSIS Pilsbry. Bulimulus corumbaensis Pilsbry, Man. Conch, ser. 2, vol. xi. p. 68, pi. xiv. figs. 3-8. The colour, as described by Pilsbry, is fairly typical, but the ground-colour may vary from " opaque white " to a vinous tint. and " the dark brown or corneous longitudinal streaks " are sometimes replaced by pellucid stripes. The form also is variable, some specimens being broader and more robust than others. Mr. Pilsbry described this species from specimens collected at Corumba by Mr. Herbert H. Smith. DRYM^US PCECILUS d'Orbigny. Brymceus pcecilus, Pilsbry, Man. Conch, ser. 2, vol. xi. p. 285, pi. xlix. figs. 49-57. This species varies considerably in size, form, and colour. Six of the seven Matto Grosso specimens are whitish or yellowish, and most have upon the body-whorl seven more or less interrupted dark zones, the four uppermost being sufficiently disconnected to appear like rows of spots, whilst the three lower ones are but very slightly interrupted. Pilsbry's figure 50 represents this form, except that the spire is hardly acuminate enough. _ His fig. 53 is rather like the seventh specimen, which, however, is still more darkly coloured. )). The Present State of Knowledge of Colour-heredity in Mice and Rats. By W . BATESON, M.A., F.R.S., F.Z.S., Fellow of St. John's College, Cambridge. [Received May 26, 1903.] With the revival of interest in the experimental study of variation and heredity which has followed the discovery of Mendel's work, Mice have naturally been chosen by several investigators as a subject for experiment. To the breeder mice offer attractions from their small size, cheapness, healthiness, and rapid rate of multiplication. They have further the great advantage. that the same male can be simultaneously tested with several females They are, however, short-lived, 1| years being a high limit of the breeding age. There are also more serious drawbacks. They are extremely addicted to eating their young. It is not easy to label a live mouse in a permanent fashion, and special |