NORTH AMERICAN BEAVERS, OTTERS AND FISHERS. 425 
Anatomical Characters.*—Size, medium (exceeded by vaga, sonora and pacifica). 
Tail relatively short. Inferior webs of feet and interspace between posterior and ante- 
rior callosities of manus, 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 bulle large, tumid, rising abruptly from the sides of basioccipital. 
Measurements.—See tables. 
Remarks.—V ariations 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. 8. 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 Hudsonian otter. Its synonymy inyolves 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. 8. Palmer at length on these questions and have 
accepted their ruling as to the first tenable name of the Hudsonian otter being Lutra 
hudsonica Lacépéde 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: Mustela lutra 
* The diagnostic value of the nose pad has no significance in this study of the relationships of a monotypic group, 
