22 Bangs The Weasels of Eastern North America. 



Skull. Skull very small and light, with the same oblong brain case and 

 large inflated squamosal as in all the richardsoni group, from which it 

 differs in exceedingly small size only. 



Remarks. This rare and little known weasel was first de 

 scribed by Baird in 1857. But Baird referred it to Mustela pusilla 

 of DeKay, with the remark, " It is barely possible that the speci 

 men here described may be different from the New York species 

 as given by Dr. DeKay." De Kay's M. pusilla was the M. cicognani 

 of Bonaparte, as shown by his description and measurements 

 and by its geographical distribution. 



P. rixosus is at present very imperfectly represented in collec 

 tions. There are a few skins in the United States National 

 Museum from points in Arctic America, from Fort Albany to 

 Alaska. Most of these skins are in poor condition and have 

 what is left of the skull inside the skin. They are also unsexed. 

 There are two very good skins from Moose Factory, Ontario, 

 made by C. Drexler (No. 5532. Museum Comparative Zoology, 

 Cambridge, Mass., and No. 4231, United States National Museum. 

 The latter is labeled male, but I think it is really a female). 

 Two of the Alaska examples are in winter pelage and are pure 

 white all over, including the end of the tail. One from the 

 upper Yukon (No. 13904, collected by E. W. Nelson) is appar 

 ently a male. All the others are apparently females. Even this 

 male, although unmeasured, is, so far as can be judged, smaller 

 than full-grown females of the European P. nivalis. 



In summer pelage P. rixosus can be distinguished from the 

 European P. nivalis by its darker color, and at all seasons by its 

 very much smaller size. 



Dr. Coues, in his ' Fur-Bearing Animals,' speaks of larger 

 examples with longer tails, the ends of which are dusky, and 

 refers such specimens to this species (which he called P. vulgaris). 

 In this he was in error, as was Professor Baird in considering 

 No. 2319 from Steilacoom, Washington, to be this animal. I 

 have seen many such, and in every case close examination has 

 proved them to be the young of either P. richardsoni or P. cicog 

 nani, with the milk dentition plainly visible. The short, closely 

 haired tails of young weasels of this group, with the end not dis 

 tinctly black, owing to the hairs of the tail not being full grown, 

 gives them a superficial resemblance to P. rixosus. But in all 

 such cases the. teeth at once tell the story. Two specimens in 

 the National Museum, No. 5686, from Big Island, and No. 5691, 

 from Fort Rae, are very good examples in point. 



P. rixosus is, I believe, the smallest known carnivorous animal. 



