NORTH AMERICAN BEAVERS, OTTERS AND FISHERS. 425 



Anatomical Characters.'' 1 — Size, medium (exceeded by vaga, sonora and pacifica). 

 Tail relatively short. Inferior webs of feet and interspace between posterior and ante- 

 rior callosities of maims, densely haired. Hind foot with claw about 125 mm. in old 

 adults ; but so variable as to have little diagnostic value. Total length rarely exceeding 

 1100 mm. Skull — size, medium (greatly exceeded by vaga and pacifica). Teeth large, 

 crowded longitudinally upon each other and obliquely overlapping. Postorbital neck 

 of frontals relatively short and wide, its superior ridge on a plane with nasals and occi- 

 pital crest. Mastoid width much less than zygomatic width. Postorbital processes short 

 and stout. Audital bulla? large, tumid, rising abruptly from the sides of basioccipital. 



Measurements. — See tables. 



Remarks. — Variations in the size of adult otters from apparently the same region 

 seem remarkable at first sight, but I find that these are not always to be attributed to sex 

 (for the female otter sometimes reaches near to the average size of the males), but to 

 environment. The otters of the Alleghany mountain streams are uniformly smaller 

 than those of the tide-water creeks and rivers of the Atlantic seaboard. This rule 

 applies from Labrador to Florida and is undoubtedly the result of the relative difficulty 

 of obtaining food and securing shelter from enemies in the two kinds of habitat. On 

 the other hand, this difference lies wholly within the limitations of individual variation 

 and in no sense affects the well-defined cranial and other characters which distinguish 

 the races and species hereafter defined. It has to do solely with size, not with propor- 

 tions. In a letter from Mr. C S. Brimley, of Raleigh, North Carolina, the same feature 

 is alluded to where he states : "A trapper of our acquaintance says that otters from the 

 saltmarshes of eastern North Carolina average considerably larger than the otters of the 

 small streams of the central part of the State." 



There is rarely to be found a case in mammalian nomenclature more puzzling than 

 that of the first tenable name of the Hudson ian otter. Its synonymy involves that of 

 the mink and the fisher as well as the questions of priority of publication of Erxleben's 

 and Schreber's great works on the Mammalia, and the tenability of plate names. I have 

 consulted Drs. C. H. Merriam and T. S. Palmer at length on these questions and have 

 accepted their ruling as to the first tenable name of the Hudsonian otter being Lutra 

 hudsonica Lacepede and that of the northeastern mink to be Putorius vison Schreber. 

 In regard to the name of the fisher, however, I prefer to abide by Canon XLIII of the 

 Code of the American Ornithologists' Union, which accepts, under certain conditions, 

 the names of species originally published on plates, which Drs. Merriam and Palmer 

 and Mr. Sherborn do not accept. Returning now to the abstract of synonymy as given 

 above for the Hudsonian otter, the case may be concisely stated thus : Musteh. lutra 



* The diagnostic value of the nose pad has no significance in this study of the relationships of a monotypic gronp. 



