402 



CARNIVORA 



brown tending to encroach on white to such an extent as 

 occasionally to pass completely across chest, and frequently to 

 form spots and blotches in same region ; upper lip usually with 

 some white ; a brown spot varying much in size, and sometimes 

 joined with brown of che(;k, usually present behind angle of 

 mouth ; ear brown like surrounding parts, the rim not 

 whitened ; tail concolor with back, the pencil faintly darker or 

 occasionally with black hairs, the median ventral region some- 

 times faintly paler than rest of tail, but never with definite 

 light stripe. In white winter j)elage the entire animal is white 

 or whitish, the tail sometimes with a few black hairs in pencil. 

 The change does not take place regularly except in the colder 

 portions of the animal's range, as in the Alps and central and 

 northern Scandinavia. 



ShiU and teeth. — The skull resembles that of Mustela ermhiea 

 in all respects except that the interorbital 

 region is often narrower than the rostrum, 

 a character most pronounced in the larger 

 races that approach M. erminea in size. 

 Postorbital process frequently more promi- 

 nent than in M. erminea, and zygoma often 

 less evenly bowed upward, its upper border 

 flattened or sometimes with a distinct median 

 concavity and posterior widening as in 

 M. putorius. Teeth not distinguishable from 

 those of Mustela erminea except by their 

 smaller size. 



Remarks. — Although the most variable of 

 the European Mustelidse this species is always 

 readily distinguishable externally from the 

 other memljers of the genus Mustela with 

 which it is associated by the short thin pencil. 

 The discrepancy in width between the rostrum and interorbital 

 region, while generally characteristic of the species as compared 

 with Mustela erminea, is not perfectly constant. It is invariably 

 well marked, however, in adults of the larger southern animals. 

 Three races are represented in Europe, a smaller northern and 

 central form, and two larger subspecies in the Mediterranean 



Mustela nivalis (male), 

 Nat. size. 



MusTKLA NIVALIS NIVALIS Linnwus. 



1766. [Mustela'] nivalis Liunseus, Syst. Nat., i, 12th ed., p. 69. 



1777. [Mustela'] vulgaris Erxleben, Syst. Regni Anim., i, p. 471 



(Temperate Europe). 

 1811. Mustela gale Pallas, Zoogr. Rosso-Asiat., p. 91 (Renaming of 



vulgaris). 

 1820. Mustela minor Nilsson, Skand. Fauna, i,p. 35 (Renaming of nivalis). 

 1853. PUdorius] mimitus Pomel, Catal. ]M6tli. et Descr. Vert. Foss. Loire, 



p. 51 (Neighbourhood of Paris, France). 



