62 MAMMALS OF UTAH 



Family MURIDAE. Rats, Mice, Voles 

 Subfamily MAURINAE 



BLACK RAT 



MUS RATTUS (Linn) 



Mus rattus, Linnaeus, Syst. Nat., 10th ed., 1758, p. 61; Elliot, 

 F. C. M., 11, 1901, p. 117, fig. 28 (skull), Syn. Mam. N. 

 Am. IV, 1904, p. 163, fig. 31 (skull), fig. 25 (animal); 

 Miller and Rehn, Proc. Bost. Soc. Nat. Hist., XXX, No. 1, 

 Dec. 27, 1901, p. 56. 



Description — The black rat is usually of a sooty or 

 plumbeous black color, paler on the underpart. 



Distribution — The black rat now appears in nearly all 

 of the older portions of Salt Lake City and adjacent low- 

 lands. It is especially common along the Jordan river and 

 in the western part of the city. Its range is gradually ex- 

 tending. It everywhere does damage of almost every con- 

 ceivable type, its ravages on the poultry farms being particu- 

 larly noticeable. 



NORWAY RAT: BROWN RAT 



MUS NORVEGICUS (Erxleben) 



Mus norvegicus Erxleben, Syst. Regn. Anim., 1777, p. 381. 

 Mus decumanus Pall., Nov. Sp. Quad. Glir., 1778, p. 91. 



Description — The brown rat differs from the other two 

 species in America in larger size, shorter head, more obtuse 

 muzzle, smaller ears, and relatively shorter tail. The general 

 color is grayish brown above and whitish below. The over- 

 hairs of the upper parts have black tips. The tail is usually 

 shorter than the head and body combined, while in the 

 other two species it is generally longer. Total length, 12.0 ; 

 tail vert., 5.6; hind foot, 1.5. (Lantz.) 



Distribution — The brown rat has unfortunately of re- 

 cent years become very common in Salt Lake City ; and its 

 range is gradually extending along railway lines. 



Habits — The marvelous rapidity with which brown rats 

 increase is shown from the fact that nests, though usually 

 containing about eight young, have been found with twenty- 

 three young ones in them; and a new litter is brought in 



