538 bulletin: museum of comparative zoology, 



Labrador animal (D. hudsoniiis). The short median black line, 

 reaching the shoulders in adults, the grayer tint of the summer pelage, 

 the reduction of the postero-internal enamel fold of the anterior 

 two upper teeth and the absence of the antero-external fold in the 

 last lower molar, separate it sharply from the continental forms of 

 nihricatus. Should intergradation be demonstrated, however, rubri- 

 catus and its various forms here recognized, would stand as subspecies 

 of groenlandicus. 



Specimens exammcd. — Four, as follows : — Greenland, Smith Sound, 

 1, skull only (U. S. X. M.). Ellesmere Land, Bache Peninsula, 2 

 (M. C. Z.).' Baffin Land, Cape Mercy, 1 (U. S. N. M.). 



