180 Mammalia, 



III. DISSECTIOIS' OF A MAMMAL. 



COMMON RAT Mus Decumanus. 



Rodentia. Muridce, 



Introductory. Mus Decumanus (Pallas), the Brown Eat, 

 Le Surmulot (Bujffon) of the FrencLi, is supposed to have 

 penetrated into Western Europe from Persia and the East 

 Indies, where it lives in burrows, about 1730 ; for it was not 

 till 1727* that, after an earthquake, it arrived at Astracan 

 by swimming across the Yolga. Though frequently styled 

 the Norway Kat, it was not known to exist in Scandinavia f 

 when the name was first applied to it. It is somewhat larger 

 than the Black Pat (Mus Pattus), which also originally came 

 from the East ; and has in many countries expelled it. 



It is of a brownish grey colour above, and a whitish grey 

 colour beneath. The Tail is furnished with annulate scales, and 

 hairs between each ring, but is on the whole thinly haired and 

 shorter than the head and body, by both of which points it 

 may be further distinguished from the Black Pat. The Ears 

 are rounded, somewhat naked, and exsert. The Eyes are late- 

 ral. The upper Lip is distinctly cleft : the Muffle is sliglitly 

 hairy but not divided by any vertical groove J separating the 

 nostrils, the only indication of which is a small seam imme- 

 diately above the incisors. The external nasal apertures, 

 underneath the muffle, are lateral, and shaped somewhat like 

 a comma. The Fore-feet are furnished with four toes, and on 

 the sole are several warts, one being especially developed, for 



* Cuvier. Buifon, viii., p. 206. t Pennant. 



t Waterhousl says, " A distinctly cleft upper lip, combined with a small 

 naked muffle, divided by a vertical groove, and separating the nostrils, is char- 

 acteristic of nearly the whole of the Great Murine and Sciurine sections" (Nat. 

 Hist. Mam. vol. ii., p. 7) ; but this does not appear to be so here. 



