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 con- 

 clusion, in agreement with Mr. Pilsbry, that the change of name 

 proposed by M. Ancey for this shell was laot necessary. 



BuLiMULUs CORUMBAENSIS Pilsbry. 



Bulimidtts corimibaensis Pilsbry, Man. Conch, ser. 2, vol. xi. 

 p. 68, pi. xiv. figs. 3-8. 



The colour, as described by Pilsbry, is fan^y typical, but the 

 ground-colour may vary from " opaque white " to a vinous tint. 

 and " the dark brown or corneous longitudinal streaks " are some- 

 times 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. 



Drymceios 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 intei-rupted 

 dark zones, the four uppermost being sufiiciently 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. 



3. The Present State of Knowledge o£ Colour-lieredity 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 investi- 

 gators as a subject for experiment. To the breeder mice ofler 

 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 breeduig 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 



