616 MURIDAS—EPIMYS 
four, Eee in one each, I~! 474 373 and 3=3,  Elmhirst 


os Jat eae Gs, 4—3 
(zz lt.) notes one from Great Cumbrae with the formula ae 
Hairless rats have been recorded by Bree (/e/d, 5th Oct. 1872, 328), 
who sent two to the Royal College of Surgeons; one, almost hairless, 
with transparent yellow skin, is mentioned by Millais (ii, 232); one 
from Leyton, Essex, is recorded by Beddard (P. Z. S., 1903, ii., 336); 
and another from Devonport by Belcher (Zoologzst, 1904, 72). 
A very large number of colour variations have been recorded for 
this species, a circumstance due to the density of the rat population 
and the enormous numbers which come under observation rather than 
to any greater instability of coloration than in allied species. Space 
will not permit of a complete list of the variations which have been 
observed among wild rats, but they may perhaps be classified as 
follows ! :— 
1. Pure albinos; white with pink eyes. 
2. Partial albinos; including silvery grey, fawn, and sandy animals, 
with or without pink eyes. 
3. Partially or completely melanic individuals. 
In some cases the variation affects the whole coat; in others it is 
only seen in portions of the coat, so that spotted, pied, or parti- 
coloured rats are the result. 
Such variations are frequently transmitted by heredity, and may 
become characteristic of local races. The most striking instance of 
this sort is, of course, that afforded by /zbernzcus discussed above. 
Lord Headley discovered a peculiar race on an island in Lough 
Corrib, Co. Galway ; eleven caught there were buff or fawn, “desert” 
coloured rats, with ruby eyes. Millais mentions sandy coloured rats 
found on the seashore of Tiree, and he compares them with the 
peculiar House Mice of North Bull, Dublin. 
E. norvegicus is frequently bred in captivity, and many variations of 
colour and pattern have shown themselves in the course of domestication ; 
these variations have been studied by Crampe, Doncaster, Mudge,” 
| Reference may be made to the following, though quite incomplete, list of the 
literature for details of representative cases :—G. B. Corbin, Zoo/ogist, 1873, 3525 ; 
J. Gatcombe, zézd., 1874, 3996; J. Sclater, zzd., 1876, 5039 ; B. H. (Llandudno), F7e/d, 
ist August 1885, 192; E. W. Gunn, Zoo/ogzst, 1889, 144; G. T. Rope, zdid., 1890, 
97; R. I. Pocock, Feld, 22nd June 1907, 1063, and 18th May 1912, 997; and A. J. 
Bengough, zézd., 2nd December 1911, 1234. Other cases are noted by Millais (ii., 
221). Cocks has seen an immature albino male in Bucks, and Service informed 
us of a light grey or grizzled white rat taken in July 1903. 
2 Crampe, Landwirth. Jahrb., 1885, 539; L. Doncaster, Proc. Camb. Phil. Soc., 
xlil., 1905, 215; G. Mudge, Proc. Roy. Soc., 80, 97, 1908. 
