OUnEU X. THE KODEXTIA. 327 



ji. Ar/rc.stis. — Tlie Field Vole. The length of tliLs species, including the 

 tail, is about five inches. The upper parts of the body arc reddisli-brown, 

 sides lighter ; the lower parts are yellowish-gray. It inhabits low and wet 

 pasture-lands and tlie banks of streams, feeding on grass, and roots, and 

 insects. In the autumn it visits fields of grain and corn, and sometimes docs 

 nuich injury. 



^■1. Protcnsis. — The jNIeadow Yt)lc. Tliis species is smaller than the 

 field vole, but resembles it in form. The color above is bright red, ycllow- 

 ish-gr.ay on the sides, and cream color beneath. In habits it is like the 

 l)rcceding. 



Of the voles there are nearly fifty species, among which arc two of imper- 

 fect vision, called hiind rats. 



Genus C.vstoh. — The Beaver. For intelligence, social instincts, reflec- 

 tive powers, and a certain degree of moral sense, this animal has long been 

 renowned. It is a bulky and strongly built creature, remarkable for the 

 great strengtli and sharpness of its incisive teeth, witii which it fells large 

 trees, and its broad, powerful, and trowel-like tail. There ai'e two species, 

 one of North America, the other of Euro[ic, limited ciiiefly to Poland, and 

 known under the title of Bohr. It is said the European species does not 

 build, and we believe no author has satisfactorily explained this non-compli- 

 ance with the constructive instinct of the genus. 



In all the Northern States of the American Union the beaver was formerly 

 common, and the ruins of his dams and dwellings are often met with, even 

 now, on the banks of rivers and brooks. In proportion, however, as civili- 

 zation encroaches on the wilderness the beaver naturally recedes, and, con- 

 sequently, is rarely found to-day in the older states. But on the northern 

 borders of the North-western States, through the entire of Canada, and 

 northern Asia, the industrious anil sagacious beaver still plies his areliitect- 

 ural trade, and establishes his commonwealth. A discriminating observer 

 says that beavers begin to assemble in the months of June and July. Tiic 

 country is previously surveyed, and a fiivorable site chosen for their opera- 

 tions, usually beside a river or brook where the waters alternately rise and 

 fall. "Here they throw up a bank, and thus construct a reservoir, which 

 uniformly remains at the same heigiit. This bank, which resembles a sluice, 

 and is frequently from eighty to one hundred feet in length, by ten or twelve 

 wide at the base, is even more astonishing with regard to its solidity than its 

 magnitude. For the purpose of constructing it, they select a shallow part 

 of the brook or river; and if they find on the margin a large tree, so situated 

 as readily to fall into the water, they begin to cut it down, their fore teeth 

 answering the purpose of a wood-cutter's hatchet ; and they begin the work 

 of felling at a foot and a half above the ground. While thus employed, the 



