et Gopher (59840-59849, 70086-70102) were trapped at
localities 3, 6, 7, 10, 11, and 13. The eight skins from locality 7
differ from those from the other localities on the Mesa in being
uniformly duller in color dorsally. No significant difference in size
or cranial characters was observed. Specimens assigned to _T. t.
fossor_, in the collection of the Museum of Natural History, from other
localities in Colorado differ in color from any of the specimens from
the Grand Mesa. Until larger numbers of _Thomomys talpoides_ from other
localities in Colorado and from the type locality of _T. t. fossor_,
stated to be at Florida, in southern Colorado, have been studied, the
specimens from the Grand Mesa seem best referred to _T. t. fossor_.
Three females from localities 7, 10, and 11 contained embryos (2, 4,
and 5 in number), and seven other females from localities 6 and 7 show
distinct mammae on the dried skins or were recorded by the collectors
as lactating.

=_Castor canadensis concisor_= Warren and Hall.--Dams constructed by
beavers were seen at locality 4 on June 23, 1954. No specimen was
taken.

=_Peromyscus maniculatus rufinus_= (Merriam).--The 36 specimens of the
Deer Mouse (59921-59956) are from seven localities (3, 4, 6, 10, 12,
14, and 15). The mice vary considerably in color; most of them are like
mice of the highlands of Colorado and unlike the paler mice inhabiting
the lower areas immediately to the west of the Grand Mesa. Young
individuals trapped on June 20, 21, and 22 and judged to range from a
month through two months in age, and females containing embryos, attest
to a somewhat protracted breeding season on the Grand Mesa.

=_Neotoma cinerea arizonae_= Merriam.--Two immature Bushy-tailed Wood
Rats (60000-60001) were obtained at locality 3 on July 3.

=_Clethrionomys gapperi galei_= (Merriam).--The 22 specimens
(60005-60025, 70133) of Gapper's Red-backed Vole were taken at
localities 6, 7, and 10, and are clearly referable to _C. g. galei_,
rather than to _Clethrionomys gapperi gauti_ to the south, on the basis
of generally dark dorsal pelage, indistinctly bordered broad dorsal
stripe, and cranial features. _C. g. gauti_ was described by Cockrum
and Fitch (1952, Univ. Kansas Publ., Mus. Nat. Hist., 5:289) on the
basis of 14 specimens from southern Colorado and northern New Mexico.
Twenty-one additional specimens from five miles south and one mile
west of Cucharas Camps, Huerfano County, were obtained from th