IV NORTH AMERICAN MUSTELID.E. 



a desirable contribution to the literature of the general subject. 

 The Mustelidce, like most other families of North American 

 Mammals, have not been systematically revised for many years^ 

 during which much new material, hitherto unused, has become 

 available for the purposes of science ; while the steady and 

 rapid progress of scientific inquiry has rendered it necessary ta 

 reopen and discuss many questions in a new light. The same 

 principles and methods of study which the author has suc- 

 cessfully applied to the elucidation of the Rodent ia of North 

 America have been brought to bear upon the investigation of 

 the MusUlidw. 



The Memoir is based upon specimens secured by the Survey 

 under my direction, together with all the material contained 

 in the National Museum, for the opportunity of examining 

 which the Survey acknowledges, in this as in other instances, 

 its indebtedness to the Smithsonian Institution. 



The illustrations of the present volume, with few exceptions,* 

 were engraved by Mr. H. H. Nichols, of WavShington, from pho- 

 tographs on wood made under Dr. Coues's direction by Mr. T. W. 

 Smillie, of Washington. This method of natural history illus- 

 tratiou may still be regarded in the light of an experiment ; but 

 the cuts may be considered fine specimens of the engraver's, 

 art, when it is remembered that photography gives no lines 

 to be followed by the graver. Though showing less detail, 

 particularly of the under surfaces of the skulls, than might 

 have been secured by hand-drawing, the cuts possess the merit 

 of absolute accuracy of contour. 



This opportunity is taken to reprint, by permission, a Circular 

 relating to the proposed "History", which was addressed by 

 Dr. Cones to the Medical Staff of the Army, of which he is a 

 member. The Circular is sufficiently explicit to require no couk 

 meut; but I may here express my high appreciation of the 

 courtesy with which the wishes of the Survey have been met 

 by the Surgeon General of the Army. 



F. V. HAYDEN, 

 United States Geologist. 



* The several ligurts on the electrotype plate VI were kindly loaned by Mr. 

 E. A. Samuel?, of Boston, from the Massachusetts Agricultural Report for 18tU. 

 The figures on plate XII were drawn on wood by Mr. S. W. Keen, of Wash- 

 ington, from photographs furnishtd by Mr. II. W. Parker, of the Agricultural 

 College, Amherst, Mass. 



