398 MR. G. E. H. BARfiETT-HAMILTON ON [Apr. 3, 



Outer Hebrides are, like the Lepidoptera of the same islands, 

 small and darkly coloured. 



In many cases black forms of some common species of animals 

 occur in the British Islands or in mountains, either in certain 

 defined areas or sporadically, but are not yet in a status 

 to be generally recognized subspecifically. Such are the black 

 variety of the Water- Vole, Microtus ater (Macgillivray) ; the 

 black varieties of the Common Eat, Mia hibernicus Thompson ; 

 the black variety of the Squirrel, Sciurus cdpinus Cuvier, of the 

 Pyrenees and Alps ; and the dark variety of the Common Snipe, 

 Gallinago ccelestis sabinii (Vigors). Such forms, however, seem to 

 be in many ways analogous, and it is strongly to be suspected 

 that they owe their origin to some common cause, apparently not, 

 in the ordinary sense, a protective one. 



1 recognize 19 subspecies or phases of Mus sylvaticus, which are 

 as follows : — 



1. MUS SYLVATICUS INTERMEMUS. 



Mus intermedins, C. J. Bellamy, Natural History of South 

 Devon, pp. 195 & 329-330, with woodcut (1839). 



Mus campestrix, J. J. J. Holandre, Faune de la Moselle, p. 2-4 

 (1830), antedated by M. campestris, A.G.Hesmarest, Mainm. Suppl. 

 p. 543 (1822), which is a Mus minutus, Pall, subsp. incert. ; see 

 De Selys-Longchamps, ' Etudes de Micromammalogie : Revue 

 des Musaraign.es, des Eats et des Compagnols, suivie d'un Index 

 methodique des Mamtniferes d'Europe' (Paris, 1839), and Barrett- 

 Hamilton, Ann. & Mag. Nat. Hist., April 1899, p. 345. 



Mus sylvaticus fossilis, P. Gervais, Zool. et Pal. Fr. p. 43 (1859). 



Mus sylvaticus auctorum. 



Type locality. Devonshire, England. 



Nomenclature fy Synonymy. The discovery that the original 

 application of the name sylvaticus by Linna?us referred to a 

 distinct subspecies, makes it necessary to search for a subspecific 

 name which shall apply to the ordinary lesser subspecies of 

 Britain and the neighbouring continental area. The name inter- 

 medins of Bellamy, although undoubtedly applied to a large 

 example, seems to be suitable for this use. It is at all events 

 appropriate to an animal which is distinctly intermediate in its 

 characters between several surrounding subspecies. 



Description. The colour of the basal two-thirds of all the hairs 

 at all ages and seasons is slate-grey, but this is concealed by the 

 terminal portions, about 2 or 3 mm. in length, which are coloured 

 quite differently and to the tints of which the animal owes its 

 general appearance. In adults the upperside is sandy reddish 

 brown, not usual!) of rich or intense tints, the lower side pure 

 white, with a very clear line of demarcation between the colours 

 of the two surfaces passing along the flanks, inner surface of the 

 thighs, fore limbs, and cheeks. Many hairs of the upperside are 

 tipped with black, especially in the median dorsal region, and 

 these black tips, becoming greatly increased id winter, constitute 



