THE DORMOUSE OR SLEEPER 359 



the animal's entire absence from that country, in which it might be 

 expected to occur locally. 



It seems probable that the animal has been prevented by some 

 barriers from reaching Ireland, Scotland, and the east of England. 

 Its distribution, identity with continental Muscardinus, and absence 

 from pleistocene deposits suggest a quite recent arrival in the south of 

 England after the separation of Ireland ; and it does not seem to have 

 had time to enter Scotland or to cross rivers, fens, and marshes such 

 as still cut it off from Norfolk (where it thrives well when introduced) 

 and Suffolk. There the river Stour, with the marshes from Nayland 

 to its mouth, appears to have been an absolute barrier to it (Laver, MS.), 

 and possibly the Tyne and its tributary, the Derwent, may have 

 exercised a similar influence in Durham and Northumberland. 



Description : — The form, skull, and general characteristics of AT. 

 muscardinus are those of its genus. It is a short, compact, yellowish 

 mouse, with rather large head, raised forehead, and long whiskers ; 

 eyes bright and very prominent ; ears with a ridge above the meatus, 

 rather short, and broadly rounded; nose rather blunt; tail reaching 

 about six-sevenths of the head and body length, thickly and evenly 

 haired without being bushy. 



The hands and feet are rather short (Plate XXII.) ; the thumbs rudi- 

 mentary ; the first toes short and clawless. The remaining digits are 

 long with well-developed terminal pads and strong short claws ; they 

 are not very unequal in length, the fingers graduating from third to 

 fourth, fifth to second, and the toes from fourth, third, second to fifth. 

 There are in each hand and foot six remarkably large and swollen, but 

 not abnormally placed pads ; there being the usual four lying at the 

 bases of the digits, including a specially large one for each rudimentary 

 thumb and short first toe ; behind the latter are a pair of large long 

 proximal pads, of which the outer plantar is particularly elongated. 



The colour of the upper side and of the anal region is brownish yellow. 

 The tints are deepest and richest on the back (where there are some 

 blackish hairs) and on the tail ; paler on the flanks, which fade to cream or 

 yellowish white on the under side ; purer on the breast and upper neck, 

 so as to form a whitish patch of variable size. The line of demarcation 

 is indistinct, and passes along the cheeks slightly above the upper lip 

 to just below each eye, thence along the flanks, leaving the internal 

 surfaces of the limbs coloured like the belly, the external surfaces like 

 the back. The tail is like the back above, slightly lighter below. 



Nothing is known of the moults. The first coat of the young, which 

 appears dorsally on the ninth day, is mouse-grey, lacking the yellower 

 tints of the adult except on the head or fore parts of the body ; it is 

 cast (judging from Lataste's remarks) on or about the fifteenth or 

 sixteenth day, when a pelage closely resembling that of the adult but 



