SHREWS. 2,23 



Extinct Gym- Extinct Insectivores, more or less closely allied to the gjnimuras, 



nuras. liave left their remains in the Tertiary deposits of France belonging 

 to the upper portion of the Eocene and the lower part of the Miocene period. 

 These extinct forms, although belonging to distinct genera from those now existing, 

 serve to show the antiquity of this group of animals : and, in common vr\t\\ many 

 othei-s, fui-ther indicate how the earlj- Tertiarj- fauna of Europe has its nearest 

 representatives in the remote islands of the Malayan Ai-chipelago. 



The Shrews. 

 Family SORICW^E. 



The elegant little creatures kno\vn as slirews, or shrew-mice as they are often 

 termed from their mouse-like form, constitute the fourth family of the true 

 Insectivores. So like, indeed, are these animals to mice and rats, that hi popular 

 estimation they are often confounded witli tliem ; although thej' are readily 

 distinguishable by their long and pointed snouts, their rounded ears, closely pressed 

 to the sides of the head, and the charactei's of their teeth. 



Though there would be little likelihood of mistaking a shrew for a hedgehog, 

 it is necessary to point out in some detail the characters on which naturalists 

 refer these groups to separate families ; since, as we have seen, the spines of the 

 hedgehogs do not form a characteristic of more tlian generic importance. 



Perhaps the most ready means of determining whether or no an Insectivore 

 belongs to the shrew family is afforded by the characters of the first pair of front 

 or incisor teeth. In all shi'ews these teeth are different from the others ; those 

 of the upper jaw (as shown in the figure) being long and generally sickle-shaped, 

 with a more or less distinct cusp at the base of their 

 hinder border : while in the lower jaw they are long ^-___^^ 



and project horizontally forwards, sometimes curving ~~~\ 



upwards at the tips. Moreover, with the single excep- 

 tion of one peculiar African species, which has a vxxda- 

 mental seventh tooth, the lower jaw of every shi-ew has 

 only six teeth on each side. 



™, , P , rf ■ , , ■<■ .■ -1 SIDE VIEW OF THE RIGHT ANTERIOR 



I he above features are sufncient to distinguish tppeb teeth of the swi.m- 



a shrew from anj^ other Insectivore ; but a few additional ming shrew fro.m uxalaska 

 characteristics may also be mentioned. Thus the first 



and second upper molar teeth of all the shrews differ Much enlarged. The first upper 



„ ,, p.iiii 1 lii incisor (the tooth on the right of 



from those of the hedgehogs and gj-mnuras by the ^j^^ g^,,.^) i^ 1^53 sickle -shaped 

 absence of the fifth or central cusp on the crown, than usual.— After Dobson. 

 Then, again, the skull of a hedgehog or gymnui-a, as 



shown in the figure of the skeleton of the former given on p. 308, has a complete 

 bonj^ bar — the zygomatic arch — running below the socket for the eye to connect 

 the upper jaw with the hinder part of the skull. In a shrew, on the other hand, 

 this bony arch, as showTi in the accompanying figure, is invariably incomplete 

 beneath the eye, owing to the absence of the cheek-bone.^ A further char- 

 acteristic feature of the shrews is the extreme length and narrowness of their skulls. 



' In one Indian hedgehog the zygomatic arch is incomplete. 



.^I^«^^lfe^ 



