8 



NORTH AMERICAN FAUNA. 



[Xo.ll 



dark area in middle of back; fore and hind feet, end of tail, and band 

 across tare including eyes) black. 



Color. Ground color pale yellowish or bufl'y above and below, 

 clouded on top of head (and sometimes on neck also) by dark-tipped 

 hairs; face crossed by a broad band of sooty black, which includes the 

 eyes; feet, lower part of legs, terminal third of tail, and preputial 

 region, sooty black; back, about midway between fore and hind legs, 

 marked by a large patch of dark umber-brown, which fades insensibly 

 into the buffy of surrounding parts; muzzle, lips, chin, a small spot 

 over each eye, a narrow band behind black facial bar. and sides of 

 head to and including ears, soiled white; anterior margin of ear near 

 base clouded with dusky. 



Cranial characters. Skull large and massive, very broad between 

 orbits, and deeply constricted behind postorbital processes, 1 which are 

 strongly developed; zygomata strongly bowed outward; audital bulhe 

 obliquely flattened on outer side; a prominent bead over lachrymal 

 opening. 



Compared with our American weasels, the skull of 1'utorins H if/ ripen 



may be told at a glance 

 by its great size, the 

 basilar length in adult 

 males averaging about 

 05 mm., and in females 

 about 02 mm. Compared 

 with P. crersmanni of 

 southern Siberia, it may 

 be distinguished by the 

 greater postinolar pro- 

 duction of the palate, 

 and by other minor cra- 

 nial characters. From 

 the common polecat of Europe (Putorius putorius) it differs in several 

 important characters, as may be seen by reference to PI. I. In P. puto- 

 rius the postorbital region is very broad, the postmolar part of the 

 palate exceedingly long, and the anterior part of the audital bullse very 

 different. 



Remarl-s. The black-footed ferret bears no resemblance whatever to 

 any other American mammal, but is very closely related to the Sibe- 

 rian Putorius erersmanni. It differs from the latter in having much 

 shorter and coarser fur, larger ears, and longer postmolar extension 

 of the palate. 



In some specimens of Putorius nigripes the pale buffy of the under 

 parts is clouded across the breast between the fore legs, suggesting the 

 dark breast of P. erersmanni. The dark facial mask encircles the eyes 



'This constriction deepens with age, as in all the weasels. It is very deep iu the 

 skull shown in the accompanying text figure (fig. 1), which is that of an old indi- 

 vidual; much less deep in the younger specimen shown on PI. I, lig. 1. 



FIG. ll'utf,rius nigripes <f ad. Trego County, Kans. 



