264 Scientific Proceedings, Royal Duhlin Society. 



the temperate conditions which at present obtain in Ireland. In my view 

 the reason why L. variabilis continues to live in the Irish plains is that 

 L. europceus has been unable to reach Ireland, and the reason why 

 L. variabilis has been driven out of the plains of Britain and of Western 

 Europe is that there L. europceus has proved too strong a competitor.' In the 

 paper above cited, this question of the reaction of one species upon another 

 has been dealt with ; but perhaps it may be mentioned here that the views 

 there advocated have received lately a rather striking confirmation. 



Crespon' long ago described a vole from the neighbourhood of Nimes in 

 the department of Gard in France under the name of Arvicola (Microtus) 

 lebrunii. Blasius, in 1857,^ said that, so far as he could gatlier from the 

 somewhat unsatisfactory description, this animal should be placed with 

 M. nivalis. There the matter rested until some little time ago, when 

 Mr. Charles Mottaz visited the locality in the interests of the British 

 Museum; and he was fortunate enough to obtain specimens of M. lebrunii. 

 These were examined by Mr. Gerrit S. Miller, who found that M. lebrunii 

 undoubtedly does belong to the M. nivalis group, and indeed to what was 

 previously known as the leucurus section* — a section which probably existed 

 in Britain during Pleistocene times. But M. lebrunii differs from all its 

 living allies in the fact that it lives at so low an altitude as 550 feet 

 above sea-level, and this " in the midst of the vine and olive region of the 

 Mediterranean coast," wliilst the other living nivaloid voles exhibit a marked 

 preference for the snow-line. Here surely is the clearest proof that mere 

 temperature has nothing whatever to do with the distribution of the nivalis 

 group, just as the tenancy of the Irish plains by L. variabilis proves that the 

 more generalized and primitive forms of the arctic or mountain Hare do not 

 require cold. 



' SoHARFF, "History of the European Fauna," 1899, pp. 136-8, 14S, 315-6. "European 

 Animals," 1907, pp. 39, 97, 139-140. In these extremely valuable works Dr. ScharfF arrives at 

 similar conclusions with regard to the relations subsisting between L. variabilis and L. curopmus, 

 and to the bearing of the former species upon the question of Pleistocene climate, to those herein 

 expressed. The standpoint from which I have approached this subject is, however, a quite different 

 one from that of Dr. Scharff. He assumes an Arctic origin for the L. varialilis group, and also 

 thinks it likely that it reached western Europe in Pliocene times. I attempt to prove that the group 

 had its origin in temperate latitudes ; and I do not believe that Z. variaiilis came into existence until 

 the Pleistocene period ; and as regards England, for reasons to be stated elsewhere, until a quite late 

 moment in Pleistocene time. So far as Dr. ScharfF's main contention is concerned, viz. that the 

 climate of the " Glacial Period " was not so severe as the prevalent theory supposes, I unreservedly 

 agree with him, not merely upon the grounds stated here and in former papers, but for many other 

 reasons with which I hope to deal in the near future. 



- Crespon, " Faune Meridionale," i., p. 77, 1844. 



^ Blasius, " Saugethiere Deutschlands," p. 362. 



* Miller, Ann. and Mug. iW. Hist., Ser, 8., vol. i., p. 101, 



