THE ST KILDA HOUSE MOUSE 



663 



buff or buffy white, this colour being clearly separated from that of the 

 upper surface by a well-marked line of demarcation. 



ant. 



ant. 



(I) (2) 



Fig, 95. — Diagram of Palate of Mm muralis (i), and Mus musculus (2).' 



The skull is slightly larger than is usual in musculus, and the 

 mesopterygoid fossa (Fig. 95) is greatly narrowed in front, the ptery- 

 goids converging anteriorly instead of being approximately parallel. 

 This character, less marked in young skulls than in adults, appears to 

 be quite constant in muralis, and it has not yet been observed among 

 the large number of European skulls of musculus examined. The 

 teeth do not differ from those of musculus. 



DIMENSIONS IN MILLIMETRES OF M. MURALIS AND F^ROENSIS:— 



1 Specimens with head and body 90 mm. or less excluded as immature. 



