Exploration of the Colorado River of the West and Its Tributaries Explored in 1869, 1870, 1871, and 1872, Under the Direction of the Secretary of the Smithsonian Institution

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260 EXPLORATION OF THE OARONS OF THE COLORADO. strong wash of tawny or mudcly-brown, quite unlike the hoary-gray of the same parts of tnlpoirks. The uncler surface is not known to be varied with patches of white, nor is there any white about the mouth, excepting the immediate border of the lips. On the contrary, the mouth-parts nre sooty or dusky, contrasting with the whife which lines the cheek-pouches. This is very much as in umbrinus, and quite cliffercnt from talpoides. The hands and feet are sometimes white, as in talpoides, but oftener merely whitish, and not eldom dusky. I have not ecn the tail pure white; it is generally dark­colored for 1 he most part, often wholly so. The fore claws average about 0.40-rather less than more. Such is the typical manifestation of this fi>rm, which I have only seen from California. We have next to trace the change by illsensible degrees into both talpoidPs ann umbrinus. Proceeding up the Pacific coast, we find an animal si,ill lilte bulbivorus in the general tone of coloration (warm-brown above ancl muddy-bellied), hut in which the mouth-part, have nearly or entirely lost. their sootiness. llere, aLo, the fore claws cnla.rrre omewhat 0 ' and from this state it is but a step to the grayer true tnlpoides, which joins with douglasi in the interior of Oregon and Washington. In the interior of California, the opposite modification begins, tending toward umbrinus, which becomes fully established in Arizona and New Mexico. llere the dark mouth-parts arc preserved and even intensified, but the color grows richer till a decidedly tawny or fulvous cast is the result. Various specimens from Fort Crook and Fort Tejon, and from Provo, Utah, are of this ambig­uous ~ort, and exhibit among themselves such variations that their labeling becomes a mutter of indifference. Some of the browner ones arc not separable at all from bulbivorus, while the ruddiness of other matches that of true fulvus. 1,be gradation of the two forms in this region is demonstrably c~mpl~)t~. Some oth~r specimens from Fort Crook are ab.olutely identical With St<.·llacoorn ones tu respect of color; the only difference I ca.u note being fhc · o.mewhat weaker claws. To the southward, on the coast, the same grad.atwn occurs, becoming established a bout San Diego. J n Lower Cali­forma, pu rc umbrinus prevails. A San Frauci C1111 t'pccimcn ln1ely received at the Smitluwuian i.s n perfect albino-snow-white all over. OOUES ON GE01\1YS AND TDOMOMYS-T. UMBHTNUS. 261 Little further discussion of the synonyr;ty of this fi1rm is requirecl than is implied in what has alrendy been ~aid. Profc sor Baird appears to have first satisfactorily iclenf.ificd the Diplostoma bulbivorum of Richardson with the animal subsequently ciescribed as Oryctomys bottce by Eydoux an<.J Gervais. Preceding authors' use of the name had been altogether compilation. Schinz'H name is a synonym upon its face, being a mere renaming of the same animal. The T. laticeps was based upon the individual peculiarities of a single peci­men, the characters of which arc more or less obscured by drying after immersion in alcohol. THOMOMYS TALPOIDES UMBRINUS, (Rich.) Coues. Gcomys umbrinus, R10u., F. D. A. i, 182!), 202; Rep. Brit. Assoc. fot· 1836, v, 1837, 157. "Cadu.do.guios, Sonthwostem Louisiaua"-more likely ToxaH."- WA'l'ttun., Charlcsw. Mag. N. II. iii, 183!), u96, f. 71 (skuii).- DJCKAY, N. Y. Fn. 1842, 92. (Compiled from Riclumlson.)- ClllNZ, Syn. Mamm. ii, 1845, 137. (Compiled from Richo.r<lson.)- LlW., Proc. Acne!. Nat. Sci. Philn. H:l&2, 162. (Compiled from Riohnrdson.) Ascom!JB umbri11us, WAON., Suppl. Schreb. iii, 1R43, 38!). (Compiled.) Pscudosto11ta ttntbrinuB, Auo. & DACJJ., iii, 1854, 307. (Compiled from Richardson.) Geomys (Thomomys) umb1-inus, Gum., SU.ug. 1855,5:10. (Compiled from Richardson.) Tltomomysttntbrinus, BAIHD, M. N. A. 1857, 399 (rodoscribecl from numerous New Mexican speoimons).­DAIRD, U. S. Mex. D. Survey, ii, pt. ii, 185!), Mt•mm. p. -.-GEnn., Cat. Bones Dr. 1\lus. 1862, 228. Geom118 fult·us, Wooon., Pt·oe. Aoad. Nat. Sci. Ph ill•. 1852, 201 (San Fmnoisco Mountnins, Arizonn.); Rep. Expl. Zuni u.url Colomdo R. 1853, 51, pl. 5 (tile same). p11e~tdostoma (Geomus) j'u~l!us, Auo. & BACH., Q. N. A. iii, 1854, 300. (Copiocl ft·om Woodhous~.) 17urmomy8 ful1ms, DAIHD, M. N. A. 1857, 402. (Doscl'ibos Wootlhom;o's typo, antl othor specamons, from Cnliforuia.)-DAmD, U. S. Mex. Dound. Smv. ii, pt. ii, 1859, Mamm. p. -.-KENN., P. R. R. Rep. x, 1B59, Whipple's Route, Mo.mm. 14, pl. 12, f. 2.-Cou~ts, Am. Nat. i, 1867, 394 (habits).-COUltS, Proo. Acad. Nnt. Sci. Phil••· 1867, 13;) (Fort Whipple, Arizona).