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Show 262 EXPLOUATION OF THE OANONS OF THE COLORADO. strongly contrasting with the white lining of the pouch. Tail usually more or less like the body. HABITAT.-South Colorado, Southern Utah and Southern Nevada, Western Texas, New Mexico, Arizona, and Lower California to Cape Saint Lucas. Southward extension into Mexico undetermined. "Louisiana.'' Description (from extensive series from the above localifies).-No other torm of the genus varies so much in color as this one. With the increase in intensity and richness of coloration of the genus to the southward, there is a corresponding ratio of variation to or from what may be hclrl the normal mean. Selecting average samples, as, for instance, some I collected at Fort Whipple, Arizona, in 1~64-'65, we observe a very rich tawny or fulvous pelage, more or less obscured on the back by a blackish area. The under parts arc of the same color, paler or of about equal intensity, with the deep plumbeous bases of the hairs showing. The ears are set in a small blackish area;, the face, and, to a less extent, the top of the head, are blackish with or .with.o~t white spots on the lips or chin, contrasting strongly wit~ the whtte hmng of the pouches. The feet are indifferently whitish or dusk . and more or less of the tail is usually colored. y ' Other specimens, by the extinction of the blackish dorsal area, become nearly concolor all over, and of so rich a hue as to almost bear the term golden-brown. There is a great similarity in many cases to the coloration of .Jnculus hudsonius or Arvicola aureola. The best-marked samples of this style before me are from Southern Arizona and Cape Sai'nt L ucas, w h ere t hI' s appears ~o prevail. D~. Woouhouse's type of" fulvus'' is entirely of this color above, wtth nea~ly wlnte belly. Specimens from the Colorado Valley exhibit another style of coloration iu their extreme pallor from th bl h' f fi 1 · t 1 ' e eae mg 0 u vous m o a pa c brownish-yellow, and with whitish bell A · fi ,, s , ( h Y· spectmen rom onora rat er Southern Arizona' as now bounded) I. s d ark -c.m namon or chestnut. -red, with b. lackis.h dorsal area· Mo re no rth er1 Y speC·i mens tend to grayer tmts; hut this graytshness has a plumbeous cast d . ffi d h · .J • ' an Is su use on t e .S luI es wit.h tawny. The belly in these cases is as pUl.e Iy h oary-gray as m. typ1ea talpozdes; and one specimen from Fort M L • l . 1 . . • . ' assacrmsctts, IS exactly rat-co o 1 e< , and md IStlngUlsbaule from pure talnoides · . · h h · . :r ' except m bemg smaller t oug It 1s apparently very old. In this speC.i men, too, the characteri.s tic' COUES ON OEOMYS AND TllOMOMYS-T. OLUSlUS. 263 markings of the mouth-parts and pouches are much obscured, and the fore claws are fully as long as in some northern examples of talpoides. Halfgrown specimens, as elsewhere in the family, are lead-colored, merely paler below. A melanistic specimen from Cantonment Burgwyn, New Mexico, is a uniform, intense, lustrous plumbago color (almost like anthracite coal), with white lips and pouches. In this form, which exhibits such variation as well as intensity of color, we observe more clearly than elsewhere the changes produced in tho shedding and renewal of the pelage. It seems to be the rule in this genus, as in Geomys, that the hair is cast from before backward by a regular progression. As already hinted, the animals appear to grow gray with age; but., besides this, each annual or seasonal coat seems to lose its richness of coloration toward the time that it is to fall off, and the fresh coat comes out more heavily tinted. It results from this, in connection with the peculiar mode of shedding, that patchy specimens are of frequent occurrence, with a sharp line of demarkation between differently-colored areas ( Geomys castanops is a notable case of this). Some examples before me are, in fact, strong "umbrinus '' in front and very fair "bulbivorus '' behind. Season, as well us age, doubtless influences the color of the pelage, but exactly to what extent I am unable to say, owing to the usual oversight of collectors in neglecting to date their labels. The geographical distribution of the species, as far as now known, is indicated in a preceding paragraph. The original locality given for umbrinus has not been checked by subsequent accounts, and is probably somewhat out of the way; Texas or New Mexico being more likely the source of the typespecimen described by Richardson. I see no occasion to question Baird's identification of the species, with which the Geomys fulvus of Woodhouse is indisputably identical. THOMOMYS CLUSIUS, Coues, nov .. t;p. SP. CnAR -Smallest lmown species of the genus. Length ( 9, adult) about 5 inches. Feet remarkably small; sole of hind foot 0. 7 5 ; palm of hand, including longest claw, 0.65. Fore claws small, weak, little curved, the |
