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Image from page 426 of "Bulletin - United States National Museum" (1877) | by Internet Archive Book Images
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Image from page 426 of "Bulletin - United States National Museum" (1877)

Title: Bulletin - United States National Museum

Identifier: bulletinunitedst5611907unite

Year: 1877 (1870s)

Authors: United States National Museum; Smithsonian Institution; United States. Dept. of the Interior

Subjects: Science

Publisher: Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off.

Contributing Library: Smithsonian Libraries

Digitizing Sponsor: Smithsonian Libraries



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Text Appearing Before Image:

Fig. 63 -Onychomys tobbidus. o,Fobe- foot; 6, Hindfoot; c, Tail (nat. size . Geographical range.—Sonoran Zone of the Elevated Central Tract. Description.—Size and proportions intermediate between those of Onychomys torridus arenicola and 0. t perpaUidus. Pelage dense and beautifully soft and lustrous. Color above cinnamon, slightly grayish, considerably darkened above by black annuli and tips to the hairs, and inclining to ochraceous on the sides. Ears with lanuginous white tufts at their anterior base; \\ ell clothed with whitish hair with a black spot on the anterior half of their con- vex surfaces. Feet (fig. 63a and 6), under parts, and end of tail white Tail (fig. 63 c) densely hairy, with a dark line of drab, mixed with hoary tips to the hairs, on upper side of basal two-thirds. Whiskers long, reaching past the shoulder; their color, mixed black and white. The measurements are shown in the accompanying tabic. There are but three individuals in the series of twenty-two specimens before me which are in the gray pelage of the young. Two of these, about two-thirds grown, taken May 29 and September 18, arc gray above and white below, with the usual black spot on the ante- rior band of the ear. Both are in summer pelage, with the gray underfur showing between the hairs of the sparse coating of the under surface. The third-specimen, taken November 23, is in winter pelage and somewhat older, with the sides tinted with drab. The pelage is white below and very dense. The shade of gray is darker in" young specimens of the subspecies torridus than in arenicola or perpaUidus, but considerably paler than in the sub- species ramona, from the Pacific coast. Seasonal variation of adults.—-There is very Little seasonal difference in coloring. Specimens taken in April, May, and June are colored almost exactly Like those captured during November and December. Perhaps the latter are a trifle more grayish or silvery. with the fur more dense and glossy. Cranial and dental characters.—-The skull, except for its smaller size, closely resembles that of Onychomys melanophrys. It measures 25.7 by 13.6 mm. (For teeth see fig. 64.) Remarks.—In coloration the subspecies torridus agrees v«iv closely with 0. melanophrys, which has a similar geographical distribution. Similarly, 0. torridus arenicola is the analogue of 0. pallescens. W e


Text Appearing After Image:

Fig. 64.—ONYCHO- MYS TORRIDUS. a, Lower MO- laes; b, Upper MOLARS.



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