MUS MURALIS Barrett-Hamilton. 



1899. Mus muralis Barrett-Hamilton, Proc. Zool. Soc, London, p. 81. 



Type in British Museum. 

 1910. Mas musculus muralis Trouessart, Paune Mamm. d'Europe, p. 146. 



Type locality. — Island of St. Kilda, Scotland. 

 Geographical distribution. — Island of St. Kilda. 

 Diagnosis. — Similar to Mus musculus, but feet and tail less 

 slender (width of hind foot at base of outer toes about 4 mm.) ; 

 skull with mesopterygoid fossa coming to a sharp point anteriorly, 

 the pterygoids nowhere parallel. 



External characters. — Except for the less slender 

 tail and more robust feet the external characters do 

 not differ appreciably from those of Mus musculus. 



Colour. — The colour is essentially as in Mus 

 musculus, though the underparts appear to be more 

 frequently a well-defined buffy white. 



Skull and teeth. — Apart from the peculiarities of 

 the palate the skull agrees with that of Mus mus- 

 culus. Mesopterygoid space conspicuously narrower 

 anteriorly than posteriorly, its lateral borders nowhere 

 approximately parallel, its width in front only one- 

 third to one-fourth that between tips of hamulars. 

 This cuneate form, though less accentuated in immature speci- 

 mens than in adults, is constantly different from that charac- 



FIG. 179. 



Jt/m muralis 

 Nat. size. 



