MAMMALS OF THE MEXICAN BOUNDARY. 



365 



sionally seen dead in the streets of El Paso, Nogales, and Tucson, 

 where it appeared to be less numerous than the roof rat ( Mus alex- 

 andrinus). In San Diego, rats were very abundant. Scores of 

 black, wliite, or, more often, particolored ones, were seen about sta- 

 bles or slaughterhouses, and were said to have been recently imported 

 from China. Among ten specimens collected about the wharves of 

 San Diego, was a single plumbeous-black individual, which agreed in 

 all respects, except color, with eastern specimens of Mus norvegicus. 

 The remaining nine had unusually long tails, in some instances longer 

 than the head and body. They were grayer than New York exam- 

 ples of Mus norvegicus. Large brown rats, probably this species, 

 were feeding about my camp, in Flagstaff, Arizona, June 1 to 3, 1887. 

 I saw dead Norway rats lying in the streets of Bisbee, Arizona, in 

 October and November, 1802. None were seen or heard of on the 

 Sonoyta River, Sonora, Mexico, no species of Mus having reached the 

 Mexican villages of that region. 



Record and mcasumnnds of 10 specimens of Mus norvegicus. 



a Color, wliite. 

 ''Color, brown. 



cColor, brown. Contained 4 fetuses. 

 <* Color, plumbeous-black. 



MUS RATTUS Linnaeus. 



BLACK RAT. 



[Mus] rattus Linn^us, Syst. Nat., 10th ed., 1758, p. Gl (original description). — 

 Elliot, Field Col. Mus., II, 1901, p. 117, fig. 28 (skull ). (Synop. Mam. N. Am.); 

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



Mus rattus, Miller and Reiin, Proc. Bost. Soc. Nat. Hist., XXX, No. 1, Dec. 27, 

 1901, p. 56 (Syst. Results Study N. Am. Mam. to close of 1900). 



Type-locality. — Sweden. 



Geographical range. — Cosmopolitan, but does not thrive where 3Ius 

 norvegicus is abundant, usually disappearing before it. 



