1909] Dixon.—A New Mouse from California. 2s 
found in the National Museum. This is seareely identifiable 
more than generically, so that the name rests on Baird’s deserip- 
tion; and this seems to apply wholly to the light-colored upland 
mouse. ”’ 
For this reason most of my comparison has been with typical 
specimens of R. longicauda taken as near Petaluma as possible. 
R. halicoetes may be distinguished from R. longicauda by its 
larger size, darker color, denser fur and particularly by the much 
darker ears and hind feet which are especially noticeable during 
hfe. The black spot on the sides of the nose and the black ring 
around the eye are also darker than in R. longicauda. R. hali- 
coetes may be told from R. raviventris by its larger size, white 
underparts and bi-colored tail which is relatively much longer. 
