6i6 MURID^— EPIMYS 



four, -^^^: in one each, ^ , llZl 3 3 ^jj^j 3 — 3 Elmhirst 

 3—3 3-3 3—3 2—3 4—3 



(/« /iV.) notes one from Great Cumbrae with the formula ^ ^ . 



3—3 



Hairless rats have been recorded by Bree {Fie/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 (/". Z. S., 1903, ii., 336); 

 and another from Devonport by Belcher {Zoologist, 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 hibernicus 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, Zoologist, 1873, 3525 ; 

 J. Gatcombe, ibid., 1874, 3996 ; J. Sclater, ibid., 1876, 5039 ; B. H. (Llandudno), /^?V/^, 

 1st August 1885, 192 ; E. W. Gunn, Zoologist, 1889, 144 ; G. T. Rope, ibid., 1890, 

 97 ; R. I. Pocock, Field, 22nd June 1907, 1063, and i8th May 1912, 997 ; and A. J. 

 Bengough, «■*?■<?., 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. Sac, 

 xiii., 1905, 215 ; G. Mudge, Proc. Roy. Soc, 80, 97, 1908. 



