THE ZOOLOGIST 



No. 829.— July, 1910. 



ON THE VALIDITY OF THE YELLOW-NECKED MOUSE 

 (MUS FLAVICOLLIS, Melch.) TO RANK AS A 

 SPECIES, AND NOTES ON MUS SYLVATICUS. 



By Gokdon Dalgliesh. 



{With Comments by J. G. Millais, F.Z.S.) 



In a previous paper of mine ('Zoologist,' 1907, p. 300) I 

 pointed out my reasons for claiming Mus flavicollis as a valid 

 species. Since this was written, other important facts have 

 come to light which tend more than ever to strengthen this 

 supposition. The discussions and arguments that have been 

 propounded as to the qualifications necessary to determine 

 " What is a species ? " are manifold, and the more one dips 

 into this intricate matter the more one seems to get hopelessly 

 bewildered. As far as can at present be seen, we always appear 

 to end at the point from which we first started. A case in point 

 might be cited with regard to the different races, species, or sub- 

 species of Colchican Pheasants. Some naturalists will regard 

 these all as separate Bpecies ; others as merely local races or 

 subspecies. The former argue that the variations are constant 

 in each individual, so, on this account, they must stand as good 

 species. The latter, regarding them merely as subspecies, do 

 so because they observe all breed inter se with each other, and 

 the offspring of these are fertile. This in itself would be con- 

 Zool. 4th ser. vol. XIV., July, 1910. u 



