In _Dipodomys ordii_, color does not seem to be correlated with amount of moisture or geography, but rather with color of soil. For example, all animals from the Bonneville Basin of western Utah, are light colored as are the soils; animals from the San Rafael Desert of eastern Utah are reddish, as is the soil. More striking extremes of this are shown by _D. o. compactus_ of Padre and Mustang islands, Texas, which is pale-colored as is the sand on which it lives, and _D. o. medius_ from east-central New Mexico and western Texas, which is reddish as is the soil there, which is derived from Permian rocks. In localities where alkaline soils are present, kangaroo rats may be found with a roseaceous cast to the pelage as a result of the action of the alkaline salts on the pigment of the hair. The roseaceous color is lost when the animal sheds the old pelage. In the dorsal and ventral stripes of the tail, I find as much variation in the species _D. ordii_ as Grinnell (1922:Fig. E, p. 14) recorded in the whole genus. In _D. o. obscurus_, _D. o. fuscus_ and _D. o. utahensis_ the stripes are complete to the distal end of the tail and dark, whereas in _D. o. pallidus_ and _D. o. celeripes_ the ventral stripe is either absent or nearly so and the dorsal stripe is pale. Color as a taxonomic character is valuable in a broad sense, and is useful in placing an individual or a group of individuals in the subspecies to which they pertain. In most subspecies studied, color was quite uniform throughout the range of the animals, but in _D. o. ordii_ and _D. o. columbianus_ color is so variable that cranial features were relied on almost exclusively for the final diagnosis. Among the subspecies of _Dipodomys ordii_ there is relatively little variation in the length of the head and body. The smallest measurement is 95.5 mm. in _D. o. idoneus_ and the largest is 118.3 mm. in _D. o. richardsoni_. The shortest tail is found to be 112.0 mm. in _D. o. celeripes_ and the longest is 154.7 mm. in _D. o. terrosus_. The length of the hind foot varies from 35.0 mm. in _D. o. idoneus_ to 44.5 mm. in _D. o. nexilis_. Allen's Rule is not operative in the species _D. ordii_. According to this rule, shorter tails and smaller feet in conjunction with a large body would be expected as the more northerly limits of the species are approached, and conversely, smaller body and larger appendages would be expected as the southerly limits of the species are approached. This is not the case, however, since the subspecies _D. o. terrosus_ ranges farthest north and has the longest tail, whereas _D. o. celeripes_, found in the central part of the range of the species, has the shortest tail. Again, in regard to the hind foot, the shortest is found in _D. o. idoneus_ which is at the extreme south of the range of the species, whereas the longest hind foot is found in _D. o. nexilis_ which occupies a nearly central position in the range.