New Subspecies of Otter from Nebraska 5 



interior is distinctly larger than that of L. c. lataxina, but smaller 

 than that of L. c. vaga or L. c. sonora. Of the Pacific coast sub- 

 species it is smaller than the average L. c. pacifica and L. c. peri- 

 clysomae and slightly larger than average L. c. brevipilosus. 



Aside from its correspondence in size, the skull of interior is 

 exceedingly like that of typical canadensis in conformation. The 

 postorbital processes are short and stout as in canadensis and 

 lataxina, not short and slender as in vaga and degener, nor long 

 and stout as in pacifica, periclyzomae and brevipilosus, nor long 

 and slender as in sonora. The audital bullae are large and tumid 

 as in the several other eastern subspecies, not flattened as in 

 pacifica and periclyzomae or reduced as in brevipilosus. It dif- 

 fers from vaga, as do the other forms, in the relatively short and 

 wide postorbital neck of frontals (which are not suddenly con- 

 stricted at base), flattish frontal plane and comparatively narrow 

 mastoid breadth with weakly developed mastoid processes. The 

 very small, weak, smooth skull of degener differs from interior 

 as from typical canadensis. It differs from pacifica and peri- 

 clyzomae in the much narrower rostrum, as does brevipilosus and 

 the eastern subspecies. In brief, the skull of interior differs 

 from that of canadensis only in the somewhat less longitudinally 

 crowded and less obliquely overlapping teeth, in this respect 

 agreeing better with the several southern and western subspecies, 

 except lataxina. 



The differences in body and cranial measurements between the 

 various subspecies of Lutra canadensis may be expressed con- 

 cretely by the following table of typical measurements of adult 

 ^(^ (except that the body measurements of brevipilosus are those 

 of an adult 5). 



