364 University of California Publications in Zoology [Vol. 12 



long-tailed mountain meadow mouse was taken, the species proving 

 common at all the higher camps except Castle Lake. We found 

 them in damp meadows where they seemed to favor especially patches 

 of hellebore with green grass growing between. No difficulty was 

 experienced in trapping them where their runways and cuttings were 

 much in evidence. Localities of capture are as follows: Jackson 

 Lake, Saloon Creek divide, south fork Salmon River, head of 

 Grizzly Creek, head of Rush Creek, head of Bear Creek, and Castle 

 Lake. 



Thomomys leucodon navus Merriam 

 Red Bluff Pocket Gopher 



Comparatively few specimens of this species were taken, the 

 greatest number beiup- twenty-six from Helena (nos. 12823-12848 . 

 with five from Tower House (nos. 12849-12853). During the sum- 

 mer they were found at only one locality, Gazelle, Siskiyou County, 

 where six specimens were taken (nos. 13477-13482). 



The leucodon group is a distinct one, easily distinguishable in 

 skull characters from its nearest relative, laticeps. by the white- 

 ness of the incisors and the fact that they project more strongly 

 forward, and by the smallness of the molars. Considerable diffi- 

 culty was experienced in deciding from the published description 

 whether or not the subspecies uncus is a well-marked form and if 

 so, whether our specimens belonged to it or to leucodon. Navus 

 is described" (Merriam, 1901a, p. 112) as being a much smaller 

 form than leucodon; but a series of topotypes from Red Bluff, in 

 the collection of the Museum of Vertebrate Zoology, shows some 

 individuals so large as rather to eliminate size as a dependable 

 point of distinction. Through the kindness of Mr. Henry W. Hen- 

 shaw, Chief of the Biological Survey at Washington, some topo- 

 types of leucodon were loaned the writer for comparison, and be- 

 tween the two sets of topotypes well-marked differences were seen 

 to exist in skull characters. The comparison further indicated 

 that the specimens from Helena and Tower Hoiise, which we have 

 put under navus, are somewhat intergradient toward leucodon. 



The coloration of specimens from Helena and Tower House in 

 winter pelage is as follows: Above, general color bistre; lighter 

 on sides, shading into color of underparts, which extends well up 

 onto the sides. Underparts varying from creamy white to buff. 



