1900.] MUS SYLVATICUS AIS'D ITS ALLIES. 401 



Monsieur F. Lataste seems to have got upon the track of some 

 such subspecies when he wrote ' that in the park of M. Foucassis, 

 Department (xironde, France, lie had taken individuals " dont ies 

 teintes foncees, meme en dessous, se rapprocbaient beaucoup de 

 celles de la souris." This variety he contrasts with one from the 

 dependencies of the obssrvatory of Pic du Midi, at an altitude 

 of nearly 3000 metres, " et dont la robe est d'un roux vif eclataut. 

 Flusieurs sujets de cette derniere m'ont ete envoyes par M. 

 Vaussenat;" but I suspect that, in the case of the first of those 

 varieties, M. Lataste had to deal with immature mice. 



2. Mus sylvaticus celtious, subsp. nov. (Plate XXV". fig. 2.) 



Type. A female, No. 0.3.11.1 (British Museum Collection), from 

 Caragh Lake, Co. Kerry, Ireland : collected by Colonel J. W. 

 Yerbury, on Nov. 27, 1894. 



Distinyuisliiny Characteristics. A small-bodied Field-mouse, with 

 a very dark upperside, caused by a great increase in the number of 

 black -tipped hairs. The underside, unlike that of M. s. hebridensis 

 and M. s. hirtcnsis, is clear white, although not so clear as in 

 M. s. wintoni, and the line of demarcation between the colora- 

 tion of the two surfaces is sharply denned. The dimensions of 

 ear and hind foot seem to show that these are slightly larger in 

 proportion to the general body-size than is the case with M. s. 

 intermedins. This subspecies no doubt intergrades with Irish 

 examples of 21. s. intermedins. Thus Col. Yerbury's specimens are 

 the most and Mr. Passingham's the least accentuated specimens 

 which I have seen. 



Skull as in M. s. typicus ; total length about 25 mm. 



Distribution. West of Britain, I have seen specimens from 

 Caragh Lake, Co. Kerry (Col. J. W. Yerbury), from Fermoyle, 

 Castlegregory, in the same county (Mr. G. A. Passingham), as well 

 as from Woodpark, Co. Galway (Mr. E. F. Hibbert). These 

 specimens are matched exactly in colour and size by three from 

 Eisken, in Lewis, Outer Hebrides (Major H. D. Thornycroft), 

 and one from Skye (Mr. J. Steele Elliott). A similar one from 

 Oporto, Portugal, collected by Mr. James Searle, may be an acci- 

 dental variety or may indicate the occurrence of this small dark 

 form in other parts of Western Europe. 



General Remarks. So long ago as 1841 the late Pev. Leonard 

 Jenyns (afterwards Blomefield) received from the County of Kerry, 

 Ireland, some long-tailed Field-mice, one of which was taken at 

 an altitude of 2500 feet. He at once noticed that they differed 

 from the typical Mus sylvaticus " in being of a darker colour, 

 smaller, and with some of the relative proportions rather less " 2 , 

 and suggested the occurrence of an interesting local race in these 

 mountains. Not being, however, in possession of a satisfactory 

 series, he wisely refrained from giving a name to his specimens. 



Then followed the age of inexactness, during which Jenyns's mice 



1 Act. Soc. Linn, de Bordeaux, xxxviii. p. 33 (1884). 



2 Ann. & Mag. Nat. Hist. vol. vii. p. 2(58, June 1841. 



