NORTH AMERICAN BEAVERS, OTTERS AND FISHERS. 419 



Color* — Winter pelage, above, including sides, dark bay or blackish brown, tip- 

 ped with chestnut or russet, becoming pure chestnut on top and sides of head and on 

 chin, jaws and sides of neck. Rump and thighs purer chestnut. Ears black. Hair of 

 feet, legs and under parts seal brown. 



Anatomical Characters. — Size, smallest of the American forms. Scaly portion of 

 tail more than twice as long as wide ; hind foot with claw about 175 mm. Skull wide 

 for its length ; maximum size of skull 136 by 99 mm. in a New Brunswick example, No. 

 31, collection of E. A. and O. Bangs. Rostrum and nasals relatively short and wide, 

 the nasal bones averaging more than half as wide as long and extending but little 

 behind the premaxillaries. Upper molar dentition wide and heavy, the crowns oblique, 

 triangular and very wide anteriorly. 



Measurements. — Of a large, typical, adult male specimen from Quebec, No. 3825, 

 collection of E. A. and O. Bangs (measurements made by collector from newly killed 

 specimen). Total length, 1130 mm. ; tail vertebrae, 410 mm. ; scaly portion of tail 

 (dry meas. from skin), 263 by 122 mm. ; hind foot, 176 mm. ; length of skull, 

 132 mm. ; breadth of skull, 93 mm.; length of nasal bones, 46 mm. ; breadth of nasals, 

 21.4 mm.-j- 



Remarks. — The above diagnosis is taken mainly from the Quebec specimen, because 

 of the authentic measurements and superior condition of the skin and pelt. The aver- 

 age beaver from the Hudson bay regions, however, is somewhat lighter colored than this 

 specimen, which, in its darkness and richness of shade, rivals the best examples of paci- 

 ficus. In size, and ratio of length to width, the skull of the Quebec specimen is typical, 

 but the nasals are too narrow to serve as a standard for canadensis, whose nasals average 

 wider than pacificus and narrower than frondator. In general terms, canadensis differs 

 from frondator in smaller size, narrower tail, much darker coloration and narrower nasals. 

 It differs from carolinensis in smaller size, narrower, longer nasals and somewhat darker 

 coloration. From pacificus it differs in smaller size, lighter coloration, wider nasals and 

 broader skull. Subspecies pacificus differs from frondator in larger size, greatly nar- 

 rowed and lengthened tail-paddle, rostrum and nasals, and in its dark coloration. In 

 color frondator is decisively and uniformly lighter than eastern canadensis and carolinen- 

 sis and western pacificus, but darkened canadensis (not melanistic) are nearly as dark as 

 pacificus. In size, pacificus is much the longest of the three, with very long hind foot 

 and tail. Its skeleton is slenderer and weaker in every part as compared with the massive 

 frame of canadensis and frondator of same age. Carolinensis is nearly of the color of 



* Ridgway's Nomenclature of Colors is the standard used throughout this paper. 



f The narrow nasals of this specimen are an exception, the average of several east Canadian speeimeus showing the 

 ratio of length to breadth as less than two to one. 



