1914] Grinnell: Distribution of River Otters in California 307 



Diagnostic Characters. — Similar to L. c. pacifica and L. c. peri- 

 clyzomae, but general size greater, pelage shorter, coloration paler, 

 and proportions of skull different, the cranium for one thing being 

 narrower and higher. 



Description of Type. — Weight before skinning. 16 pounds. 10 

 ounces. Total length, 1158 millimeters; caudal vertebrae, 447; hind 

 foot. 123.5; height of ear from crown. 20; ear from notch, 23.8. 

 Length of hair : on middle of back, 21 ; top of head between ears, 11 ; 

 top of tail along median line half-way toward tip, 20.5 ; middle of 

 belly, 16.4. Length of fur: on middle of back, 13.8; top of head, 8.1; 

 top of tail, 9; belly, 9.8. Coloration (nomenclature, that of Ridgway's 

 Color Standards. 1912) : above bister, with hairs distinctly paler 

 tipped, giving a grizzled effect, gradually paling around sides to 

 Saecardo's umber on lower surface of body and tail; this further 

 paling anteriorly to avellaneous on throat and to tilleul-buff on chin 

 and upper lip ; tops of fore and hind feet snuff brown ; whiskers chiefly 

 whitish. Skull small (see table of measurements) ; rostral portion 

 relatively both narrow and shallow ; braincase narrow and high : ratio 

 of height of skull at bulla to mastoid breadth 64 per cent; dentition 

 light, 



Remarks. — Lutra c. pacifica Rhoads (1898. p. 429), type from Lake 

 Keechelus, Kittitas County, Washington, is evidently a large race, very 

 similar to L. c. perielyzomae Elliot (1905, p. 80), type from Queen 

 Charlotte Islands. British Columbia. The differences between these 

 two must be very slight. In fact Heller (1909, p. 262), after examin- 

 ing good series in the national collections at Washington, was able to 

 find but one "reliable character" to distinguish perielyzomae from 

 pacifica, namely "the extreme flatness of the audital bullae." The 

 bullae of brevipilosus are much smaller, but relatively somewhat more 

 elevated, than in British Columbian examples of perielyzomae. 



The type of brevipilosus is extreme in all skull characters (see 

 pi. 14), so that it probably represents the farthest southern divergence 

 of the Pacific Coast series of forms. The Humboldt County speci- 

 mens are very similar, as shown in the table of measurements here- 

 with given of Californian skulls. The live Oregon skulls arc somewhat 

 intermediate towards the pacifica-periclyzomae style; but because of 

 their small size I should apply the name brevipilosus to them, along 

 with all the Californian specimens. Characters of pelage and color 

 are likely to prove intermediate also, though this surmise is practically 

 worthless in absence of skins from Oregon and Washington. The three 



