Page:Natural History (1848).djvu/216

206 the equator to the coldest latitudes, they tenant rocks and mountains, plains and woods, feeding on grain and vegetables, and often devastating the cultivated domains of man...... Most are nocturnal, or crepuscular in their habits&#59; many dwell in burrows&#59; some conceal themselves amidst herbage, some amongst the foliage of trees, and some build for themselves habitations, which have excited the interest and admiration of man."

We may consider the Rodentia as constituted of five Families, Sciuridæ, Muridæ, Castoridæ, Hystricidæ, and Leporidæ.

The most elegant and sprightly of all the Rodentia are the numerous and widely-scattered species of the present group. They are known by having simple molar teeth with tuberculous crowns&#59; the lower incisors much compressed. Their number and arrangement are as follows :— Inc. $2⁄2$; can. $0⁄0$; mol. $5—5⁄4—4$;=22. The toes are long, with sharp and hooked claws, four on each fore-foot, and five on the hind: there is, however, the rudiment of a thumb on the fore paw. The presence of well-developed collar-bones (clavicles), gives much power and versatility in the use of these paws as hands. In feeding, the Squirrels usually sit upon the haunches, and holding the food between the rudimentary thumbs of both paws, nibble at it till it is consumed. The ears