76 REPORT OF NEW JERSEY STATE MUSEUM. 



Too well known about houses, but often trapped, in summer 

 at least, at long distances from houses, though in open farming 

 districts. 



Mus musculus Abbott, Cook's Geol. of N. J., 1868, p. 758. — 

 Rhoads, Proc. Acad. Nat. Sci. Phila., 1897, p. 28. — Rhoads, 

 Mam. Pa. and N. J., 1903, p. 218. 



Mus norvegicus Erxlebon. 



Norway Rat. 



PivATEs 31 AND 26, Fig. I. 



Length 18 inches. Heavily built, head thick, ears moderate, 

 tail medium, shorter than head and body. Color yellowish 

 brown, thickly interspersed with long black hairs, grayish white 

 below. Tail very sparsely haired with the scales ver}^ conspicu- 

 ous, ears dull brown. Young dull gray with no^ brown tints. 



Abundant everywhere about the habitations of man and 

 sometimes at some distance from them. The old ones slightly 

 resemble the wood rat, while the half-grown young closely re- 

 semble the rice-field mouse. The distinctions are pointed out 

 under these species. 



The Norway rat seems to have everywhere exterminated or 

 crowded out the black rat, Mus rattiis, which was the first emi- 

 grant rat tO' establish itself in many places. I know of no sur- 

 viving colonies in the State. 



Mus decumanus Abbott, Cook's Geol. of N. J., 1868, p. 758. 

 — ^Rhoads, Proc. Acad. Nat. Sci. Phila., 1897, p. 28. — Rhoads. 

 Mam. Pa. and N. J., 1903, p. 218. 



Family CASTORID^. 



The Beavers. 



These curious animals are the largest North x\merican ro- 

 dents. They are thoroughly acquatic with a curious broad, flat 

 tail and webbed feet. 



In the structure of their legs they belong nearer tO' the squir- 

 rels than tO' the mouse tribe, having the bones of the lower legs 

 separate and not fused together. 



