622 



INSECTIVORA 



their homology is exceedingly difficult to determine. Three molars 

 are invariably present, of which the third is much the smallest. In 

 the mandible there are always six teeth, but in one species of 



Myoswex there may be a seventh. 

 The first lower incisor is usually 

 directed horizontally forwards ; the 

 second incisor (formerly reckoned as 

 the canine) is the smallest tooth of 

 the series, the fourth premolar being 

 slightly larger. 



This family, which includes con- 

 siderably more than half the re- 

 presentatives of the order, has a 

 distribution coextensive with the 

 latter. Many classifications of this 

 FIG. 286. -Left lateral view of the difficult group have been attempted, 



cranium and mandible of Sorex vercepacis. -, j ji i o. 



In the cranium- i, first incisor ;c, fourth but according to the latest proposal 



incisor ; p, canine ; m, fourth premolar : of Dr. Dobson, 1 the genera may be 



in the mandible-i, first incisor; c second divided into tWO Subfamilies, dlS- 

 incisor; p, fourth premolar; m, first molar. . . . . 



(From Alston, Proc. Zooi. Soc. 1877.) tmguished by the apparently trivial 



character of the colour of the teeth. 



Subfamily Sorieinse. Summits of the teeth coloured red. 



Sorex. 2 Dentition : i 4, c , p f, m -f ; total 32. Openings of 

 male and female generative organs separated from the anal orifice ; 

 penis cylindrical or tapering ; ear well developed ; tail long, 

 covered with equal or subequal hairs. 



It has been shown by Brandt that the position of the pre- 

 maxillo-maxillary sutures in the type of the genus is between the 

 fourth and fifth tooth, so that it appears that we must regard this 

 genus as differing from all other Eutherian mammals in having four 

 upper incisors. Dr. Dobson, in his paper quoted, classes the tooth 

 here reckoned as the upper canine with the premolar series in all 

 the Shrews. Habits terrestrial. Species numerous, inhabiting the 

 Palaearctic and Nearctic regions. 



Of the two species found in the British Isles the Common 

 Shrew (S. vulgaris, Fig. 287) is by far the most common in England, 

 and is about the size of the House Mouse, to which it approximates 

 in general form. The body is clothed with close long fur, very 

 soft and dense, and varying in colour from light reddish to dark 

 brown above, rarely speckled or banded with white. The under 

 surface of both the body and the tail is grayish. The basal four- 

 fifths of all the hairs above and beneath are dark bluish-gray ; the 

 hairs of the tail are less densely set and coarser. On each side of 

 the body, at a point about one-third of the distance between the 

 elbow and the knee, may be found, especially in the rutting season, 

 1 Proc. Zool. Soc. 1890, p. 49. 3 Linn. Syst. Nat. 12th ed. vol. i. p. 73 (1766). 



