392 MB. G. E. H. BARRETT-HAMILTON ON [Apr. 3, 



(besides several specimens in alcohol) 7 skins from Co. Dublin and 

 the north of Co. Wicklow, 7 from Co. Louth, two without locality, 

 and an immature skin from Co. Galway. 



From the Channel Islands I have a set collected by Mr. W. 

 Eagle Clarke on Alderney '; while from the Continent of Europe, 

 its Islands, and North Africa, I have seen 169 specimens (which 

 form part either of my own collection or of that of the British 

 Museum of Natural History) from the following countries : — 

 Morocco 11, Portugal 9, Spain (various localities) 10, France 

 (various localities) 18, Belgium 10, Holland 5, Denmark 5, Scan- 

 dinavia 6, Germany 60 (from various localities), Lithuania 1, 

 Slavonia 10, Switzerland 11, Italy 4, Corsica 2, Sicily 2, Algeria 1, 

 Boumania 44, Montenegro 1, Bussia 1, Iceland 1. Lastly, there 

 is the series of 66 specimens kindly sent over for my examination 

 by Mr. (1. S. Miller, Junior, which comprises 16 from Brunswick, 

 Germany : 9 from Bergen, Norway ; 2 from Upsala, Sweden ; 

 17 from Switzerland; 17 from Warenne, Belgium ; and 5 from 

 Cadillac-sur-Garonne, France. 



Of Asiatic material I have examined 25 specimens from a number 

 of localities, the most eastern of which is Kuatun, in North-west 

 Fokien, China, whence Messrs. C. B. Bickett & J. D. La Touche 

 have recently sent a tine series to the Natural History Museum. 



General Remarks. — It is extremely hard to deal satisfactorily 

 with the various phases of Mus eylvaticus. Considerable as has 

 been the material at my command, far more so probably than 

 has fallen to the lot of any other naturalist to examine, it is 

 still impossible to trace out with anything like completeness the 

 variations of this species even in Western Europe. Mus sylvaticus 

 occurs everywhere in such abundance and is so easily caught 

 that it might be thought that no animal would be easier to work 

 out ; but this is not the case, for in proportion to the very facility 

 with which it is captured, a great deal of the material is young 

 and untrustworthy. At present, therefore, I do not see my way 

 to catalogue with anything like completeness the various recog- 

 nizable subspecies and individual variations. All that I can do is 

 to describe a few of the more extreme forms, leaving the majority 

 of the intermediates for further consideration. 



In dealing with the variations of an animal, we have two distinct 

 types to treat of, viz., those which are spasmodic and affect only 

 he individual, and those which are geographical and characteristic 

 of all, or of the majority of, the individuals of a particular region 

 or locality. The former do not directly concern the student of 

 geographical variation ; the latter are the species and subspecies, 

 according to the degree of difference which they show, of a paper 

 like the present one. The occurrence of startling variations, either 

 individual or geographical, seems almost foreign to the constitution 

 of Mus sylvaticus, yet it is not deficient iu equally interesting, 

 although less conspicuous, developments. In this respect, what 

 I stated in my previous paper on the subject may still, broadly 

 1 See Proc. Zool. Soc. Feb. 7, 1899, p. 82, footnote. 



