of the British Shrews. 27 



the distinguishing character of a peculiar species (S. constrietus, 

 Herm.), which; however, according to Duvernoy, who has examin- 

 ed the original specimens still preserved in the Museum at Stras- 

 burg, proves to be nothing more than the young of S. araneus and 

 S. fodiens. In fact, this is a character likewise affected by age, if 

 not altogether dependent upon it. The elongated bristly hairs above 

 spoken of are rarely found quite at the origin of the tail, or, if pre- 

 sent, are shorter here than elsewhere and more closely appressed. 

 Hence at this point the tail appears thinner ; but, from the circum- 

 stance of the hairs falling in advanced life, the difference becomes 

 less and less obvious, and in some instances at length ceases to be 

 observed. 



I now proceed to notice the different types of dentition which M. 

 Duvernoy has observed in these animals, after which I shall describe 

 more at length the characters of the teeth as exhibited by the species 

 found in our own country. 



These types, which are three in number, are regarded by M. Du- 

 vernoy as indicative of so many sub-genera, or at least well-marked 

 sections in the old genus Sorex. 



I. The first, to which he continues the name of Sorex in a re- 

 stricted sense, is distinguished by having the two middle incisors in 

 the lower jaw with an entire or simjde edge, the two corresponding 

 ones in the upper hooked, or furnished with a spur appearing- as a 

 point behind; the three or four small teeth which follow, in the up- 

 per jaw, diminishing rapidly in size from the first to the last ; none 

 of the teeth coloured — To this type belong, amongst other species, 

 the Sorex araneus of Continental authors, and the S. leucodon of 

 Hermann. 



II. The second type (Hydrosorex, Duv.) has the lower middle 

 incisors with the edge denticulated ; the upper ones forked, the spur 

 being prolonged into a hook (en crochet ;) the small molars above 

 which are five in number, diminishing insensibly from the first to the 

 last : all coloured at the tips. — Of this group the S. fodiens of Pallas 

 is considered as the typical species. M. Duvernoy includes also the 

 S. tctragonurus of Hermann. 



III. The third type possesses characters in some measure con- 

 necting it with each of the two former, on which account it is nam- 

 ed by M. Duvernoy Amphisorex. It is distinguished by the lower 

 incisors being simple, and the upper ones hooked, as in the first type • 

 but the first two of the small intermediate teeth (which are four in 

 number) are equal, the third somewhat less than these, the fourth 

 rudimentary: the tips of the incisors, as well as those of the molars. 



