mi. W San Vicente, 1 (UM); Johnson's Ranch, Big Bend Rio Grande, 4

(2 TCWC; 2 UM); mouth Santa Helena Canyon, 3 (1 TCWC; 2 MVZ).

=Dipodomys ordii fuscus= new subspecies

_Type._--Male, adult, no. 93886, U. S. Nat. Mus., Biol. Surv. Coll.; Juamave, Tamaulipas, Mexico; obtained on June 3, 1898, by E. W. Nelson and E. A. Goldman, original no. 12437.

_Range._--Nuevo León, extreme northern Zacatecas, Tamaulipas and northern San Luis Potosí, Mexico; marginal occurrences are: Coahuila, La Ventura; Tamaulipas, Tula, Juamave and Nuevo Laredo.

_Diagnosis._--Size medium (see measurements). Color dark, entire dorsal surface (_a_) between Cinnamon-Buff and Clay Color, purest on sides, flanks and cheeks, upper parts strongly suffused with black; posterior surfaces and fold of pinnae of ears, white; arietiform markings, plantar surfaces of hind feet, inside of pinnae of ears, dorsal and ventral stripes of tail, blackish. Skull of medium size; nasals relatively short; interorbital width narrow; auditory bullae relatively as well as actually greatly inflated posteriorly, laterally and ventrally; braincase vaulted; zygomatic arches light and straight; pterygoid fossae ovoid; rostrum short and wide.

_Comparisons._--From _Dipodomys ordii palmeri_, _D. o. fuscus_ differs in: Size larger; color lighter; skull larger; rostrum shorter and wider; interorbital width less; nasals shorter; auditory bullae more expanded laterally, posteriorly and ventrally; interparietal region narrower; pterygoid fossae more circular; upper incisors wider at cutting edge; zygomatic arches straight rather than bowed laterally.

From _Dipodomys ordii obscurus_, _D. o. fuscus_ differs as follows: Size larger; color lighter; skull larger; rostrum wider and shorter; interorbital region wider; width across maxillary arches greater; auditory bullae more expanded laterally, posteriorly and ventrally; zygomatic arches light and straight instead of heavy and bowed laterally; pterygoid fossae more nearly circular; braincase more vaulted; foramen magnum smaller.

From _Dipodomys ordii ordii_, _D. o. fuscus_ differs in: Size larger; color darker; skull larger; rostrum shorter and wider; nasals short and more flared distally; interorbital width greater; auditory bullae more inflated posteriorly, laterally and ventrally; interparietal region narrower; width across maxillary arches greater; pterygoid fossae larger and more nearly circular; braincase more vaulted.

From _Dipodomys ordii sennetti_, _D. o. fuscus_ can be distinguished by larger size, longer tail, darker color, and cranially by larger auditory bullae, longer nasals, wider interorbital region and greater width across maxillary arches.

_Remarks._--This dark subspecies of _Dipodomys ordii_ is most closely allied to _Dipodomys ordii palmeri_ from, which it can be distinguished by the characters set forth under comparisons.

It seems that the Rio Grande serves as a barrier to the dispersal southward of kangaroo rats from the north side and vice versa. _D. o. fuscus_ ranges from the type locality to Nuevo Laredo and has not been found on the north side of the river, being replaced there, up-river, by _Dipodomys ordii medius_ and down-river by _Dipodomys ordii sennetti_.

_Specimens examined._--Total, 53, distributed as follows:

=Coahuila=: San Juan Neponuceno, 5 mi. N La Ventura, 4 (MVZ); La Ventura, 7 (USBS).

=Tamaulipas=: Nuevo Laredo, 2 (USBS); Miquihuana, 14 (4 USBS; 9 MVZ; 1 AMNH); Juamave, 8 (USBS); Tula, 5 (UM); 3 mi. N Lulú, 5 (MVZ): Lulú, 8 (MVZ).

=Dipodomys ordii longipes= (Merriam)

_Dipodops longipes_ Merriam, N. Amer. Fauna, 3:72, September 11, 1890.

_Perodipus ordii_, Allen, Bull. Amer. Mus. Nat. Hist., 5:71, April 28, 1893 (part--the part from Bluff, Utah).

_Cricetodipus longipes_, Trouessart, Catalogus Mammalium, 1:581, 1897.

_Perodipus longipes_, Elliot, Field Columbian Museum, Zool. Ser., 2:239, 1901.

_Perodipus ordii longipes_, Goldman, Proc. Biol. Soc. Washington, 30:113, May 23, 1917.

_Dipodomys ordii longipes_, Grinnell, Journ. Mamm., 2:96, May 2, 1921.

_Dipodomys ordii cleomophila_ Goldman, Journ. Washington Acad. Sci., 23:469, October 15, 1933, type from 5 miles northeast of Winona, Coconino County, Arizona.

_Type._--Male, no. 17703/24639, U. S. Nat. Mus. Dept. Agric. Coll.; foot of Echo Cliffs, Painted Desert, Arizona; obtained on September 22, 1889, by C. Hart Merriam, original no. 512.

_Range._--Southeastern Utah, northeastern Arizona to immediately south of the Little Colorado River, northwestern New Mexico and extreme southwestern Colorado; marginal occurrences are: in Arizona, 20 mi. NE Lees Ferry, Foot Echo Cliffs in Painted Desert, 5 mi. NE Winona, Winslow and Holbrook; in New Mexico, 10 mi. SW Quemado, Riley, Laguna, Chama Canyon and Shiprock.

_Diagnosis._--Size large (see measurements). Color dark, entire dorsal surface between (_16''_) Pinkish Cinnamon and Cinnamon-Buff, purest on sides and flanks with but slight suffusion of black on upper parts; cheeks white; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral stripes of tail, brownish. Skull large; rostrum long and narrow; nasals long and thin; auditory bullae greatly inflated; styloid processes project on ventral surface of auditory bullae beyond middle of external auditory meatus.

_Comparisons._--From _Dipodomys ordii chapmani_, _D. o. longipes_ differs as follows: Size larger; color lighter; skull larger in all measurements taken; auditory bullae much more inflated.

From _Dipodomys ordii cupidineus_, _D. o. longipes_ differs in: Size larger; color lighter; rostrum longer and narrower; nasals longer; interorbital width greater; breadth across zygomatic processes of maxillae greater; auditory bullae more inflated; zygomatic arches heavier and more bowed laterally.

For comparisons with _Dipodomys ordii medius_ and _Dipodomys ordii nexilis_ see accounts of those subspecies.

_Remarks._--The large reddish _Dipodomys ordii longipes_ is notably distinct from those subspecies which have adjoining ranges. The subspecies closest, geographically and morphologically, is _Dipodomys ordii nexilis_ with which _D. o. longipes_ intergrades, in size of body and color of pelage, north of the San Juan River, Utah. This intergradation is probably the result of a migration of _D. o. longipes_ around the head waters of, or above the place in, the river where there is constantly flowing water. It is probably impossible for these animals to cross a constantly flowing stream as wide as the San Juan is in its lower reaches. The San Juan River, however, in 1896, and again in 1934, was so low that it ceased to flow below Aneth (Gregory, 1938:6, 19). Consequently, at these times, _Dipodomys_ could have crossed the river from one side to the other, at least above the Goosenecks. Intergradation is noted also with _Dipodomys ordii medius_ at Chama Canyon, New Mexico, where the color is like that of _D. o. medius_, although the cranial characters are as in _D. o. longipes_; specimens from Chama Canyon are referred to the latter. Ten miles southwest of Quemado and at Riley, New Mexico, intergradation with _Dipodomys ordii ordii_ occurs in the shape of the nasals and the intermediate size of the skull. In color and external measurements these animals more closely resemble _D. o. longipes_.

Goldman (1933:469) described _Dipodomys ordii cleomophila_ from 5 miles northeast of Winona, Coconino County, Arizona, and gave as distinctive characters "upper parts distinctly darker, ... black facial markings more distinct; skull slightly different." These comparative statements were made in reference to _Dipodomys ordii longipes_. While it is true that the animals which Goldman examined are darker and show some slight cranial differences, these animals, in my opinion, are not sufficiently distinct to warrant their separation from _D. o. longipes_. In the degree of expansion of the auditory bullae, the width of the rostrum, the length of the nasals and interorbital width, animals from 5 miles northeast of Winona (2 specimens) are within the range of individual variation shown by _D. o. longipes_. The color is darker, being more as in _Dipodomys ordii chapmani_. Specimens examined from 10 miles north of Angell, Springerville, Tanner Tank and Cedar Ranch Wash, Arizona (listed by Goldman as referable to _D. o. cleomophila_), and those from Wupatki Ruins, Arizona, agree with _D. o. longipes_ except that the width across the maxillary arches is greater. This greater width across the maxillary arches and the darker color of animals from Winona and Wupatki Ruins, in my opinion, afford insufficient basis for the recognition of the subspecies _Dipodomys ordii cleomophila_ Goldman which, therefore, is placed as a synonym of _Dipodomys ordii longipes_ (Merriam).

_Specimens examined._--Total, 244, distributed as follows:

=Utah=: _San Juan County_: 1 mi. N Bluff, 3500 ft., 1 (UU); 1/2 mi. N Bluff, 3300 ft., 7 (UU); Bluff, 2 (UU); Johns Canyon, San Juan River, 5150 ft., 2 (UU).

=Arizona=: _Coconino County_: 20 mi. NE Lees Ferry, 1 (USNM); 2 mi. S Endische, 2 (MVZ); 2 mi. SE Endische Spring, Navajo Mountain, 1 (MVZ); 1/2 mi. W Navajo Spring, Echo Cliffs, 4 (MVZ); 5 mi. S Navajo Mountain, 2 (MVZ); 7 mi. SE Navajo Mountain, 1 (MVZ); Moa Vae, 10 (MVZ); 2 mi. S Grand Canyon Bridge, 1 (USBS); Tuba, 4 (1 USBS; 3 AMNH); 12 mi. above mouth of Moencopi Wash, 2 (USBS); 14 mi. NW Cedar Ridge, 1 (USBS); 5 mi. N Cameron, 1 (MVZ); Painted Desert, 6 mi. NE Cameron, 1 (MVZ); 5 mi. E Little Colorado River on Tuba road, 2 (MVZ); Cameron, 4200 ft., 17 (8 LACM; 9 MVZ); Wupatki Ruins, 4 (MVZ); Deadmans Flat, 6400 ft., NE San Francisco Mt., 3 (MVZ); 3 mi. NW Winona, 4 (USBS); 5 mi. NE Winona, 2 (USBS); 10 mi. N Angell, Walnut Tank, 8 (USBS); Cedar Ranch Wash, 3 mi. above mouth, 5 (USBS); Tanner Tank, 2 (USBS); Tanners Crossing, Painted Desert, 1 (USBS). _Navajo County_: Right fork, Segi-ot-Sosie Canyon, 11 mi. NW Kayenta, 2 (MVZ); Bat Woman Canyon, 13 mi. W Kayenta, 1 (MVZ); Kayenta, 4 (USBS); Segi Canyon, 12 mi. WSW Kayenta, 1 (MVZ); Segi Canyon, 13 mi. WSW Kayenta, 1 (MVZ); Oraibi, 6000 ft., 9 (4 USBS; 5 MVZ); Walpi, 2 (USBS); Keam Canyon, 12 (6 USBS; 3 USNM; 3 MVZ); Winslow, 6 (USBS); Zuni Well, 7-1/2 mi. N Adamana, 9 (MVZ); Holbrook, 10 (USBS); Long Canyon, 3 (AMNH); Bubbling Springs, 2 (AMNH). _Apache County_: Dinnehotso, 5000 ft., 3 (MVZ); Lukachukai, 1 (USBS); Chin Lee, 6 (USBS); 9 mi. SW Chin Lee, 1 (USBS); 7 mi. from mouth, Canyon de Chelly, 1 (USBS); Fort Defiance, 2 (USNM); Ganado, 1 (USBS); Springerville, 2 (USBS); 3 mi. SE Springerville, 5 (USBS); unspecified, 4 (2 USBS; 2 USNM); Trash Tank, Grand Canyon, 2 (USBS).

=New Mexico=: _San Juan County_: Ship Rock, 4 (USBS); Fruitland, 9 (USBS); Blanco, 1 (USBS); Chaco Canyon National Monument, 4 (MVZ). _Rio Arriba County_: Chama Canyon, 1 (USBS). _McKinley County_: 2