mi. NE Calva, Oracle and Calabasas; in Sonora, Nogales; in

Chihuahua, Casas Grandes, Corralitos and Santa Rosalia; in Texas, 16 mi. E Van Horn and 30 mi. N Van Horn; in New Mexico, 40 mi. N Roswell, 40 mi. SE Corona and Mangos Valley.

_Diagnosis._--Size small (see measurements). Color dark, entire dorsal surface (16'') between Pinkish Cinnamon and Cinnamon-Buff, purest on sides and flanks, upper parts suffused with black; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral stripes of tail, brownish-black. Skull of medium size; rostrum narrow and relatively long; braincase flattened; auditory bullae but slightly inflated; zygomatic arches slender and straight; upper incisors short and narrow.

_Comparisons._--From _Dipodomys ordii richardsoni_, _D. o. ordii_ differs as follows: Size smaller; color somewhat lighter; dorsal and ventral stripes of tail brownish instead of blackish; skull smaller in all measurements taken.

From _Dipodomys ordii montanus_, _D. o. ordii_ differs in: Size smaller; color lighter; skull narrower across bullae and rostrum; wider interorbitally; all other measurements taken the same, thus imparting to the skull, in dorsal view, a longer, narrower appearance.

From _Dipodomys ordii chapmani_, _D. o. ordii_ differs in: Size smaller; color lighter; skull smaller; zygomatic arches narrower at suture of jugal and zygomatic process of maxillary; rostrum narrower; upper incisors smaller; nasals shorter; least interorbital width less.

For comparisons with _Dipodomys ordii sennetti_ and _Dipodomys ordii compactus_ see accounts of those subspecies.

_Remarks._--Intergradation occurs with _Dipodomys ordii chapmani_, _Dipodomys ordii longipes_, _Dipodomys ordii medius_ and _Dipodomys ordii attenuatus_. Only along the Rio Grande near El Paso, Texas, are individuals of a population uniform. On the periphery of the range, specimens from a given locality may resemble _D. o. ordii_ or _D. o. longipes_ or may be intermediate between these two subspecies.

Animals from the Organ Mountains near Globe Springs, 20 miles north of Cliff, New Mexico, and those labeled with reference to Van Horn, Texas, on the average are darker, have a wider expanse across the auditory bullae, a wider interorbital region and, in most specimens, more distally flared nasals than the norm of other populations. This deviation from the normal is interpreted not as intergradation with any other subspecies but rather as individual variation in a given population.

Specimens from 40 miles southeast of Corona and 10 miles northeast of Socorro, New Mexico, show intergradation between _D. o. ordii_ and _D. o. montanus_ in size of body, configuration of nasals and cranial size. For a discussion of intergradation with _D. o. longipes_, _D. o. medius_ and _D. o. chapmani_ see the remarks in the accounts of those subspecies.

Specimens from Cananea and Santa Cruz, Sonora, Casas Grandes Viejo, Chihuahua City and Colonia Diaz, Chihuahua, are not typical of _D. o. ordii_ but rather show the influence of some race probably to the southeast that is as yet unknown. In a series of nine specimens from near Casas Grandes Viejo, Chihuahua, four individuals are typically _D. o. ordii_, four resemble an apparently undescribed form and one specimen is intermediate between _D. o. ordii_ and the unnamed subspecies. This unnamed race differs from _D. o. ordii_ in having darker pelage, darker dorsal stripe on tail, larger body, wider interorbital region, longer skull, greater breadth across the bullae, less vaulted braincase, more robust zygomatic arches and the foramen magnum more deeply notched on both the dorsal and ventral rims. It seems that these animals mentioned above should be referred to _D. o. ordii_ at least until such time as material becomes available from eastern Chihuahua, northern Coahuila and northeastern Durango.

_Specimens examined._--Total, 451, distributed as follows:

=Arizona=: _Gila County_: Rice, 2 (USBS). _Maricopa County_: Marinette, 8 (CAS). _Pinal County_: Oracle, 4 (USBS). _Graham County_: 20 mi. NE Calva, 5 (USBS); Fort Grant, 11 (7 USBS; 4 MVZ). _Pima County_: Ft. Lowell, 3 (DRD); 11-1/2 mi. S Tucson, 1 (MVZ); Continental, 20 (8 USBS; 12 DRD); La Osa, 11 (USNM); Babiquivari Mountains 10 mi. N International Boundary, 1 (DRD). _Santa Cruz County_: 2 mi. S Tumacacori Mission, 1 (DRD); 7 mi. N Patagonia, 4500 ft., 12 (CAS); 3 mi. N Patagonia, 1 (CAS); Calabasas, 7 (6 USBS; 1 USNM). _Cochise County_: 8 mi. W Bowie, 1 (LACM); Wilcox, 4163 ft., 25 (12 USBS; 5 UM; 4 MVZ; 4 USNM); 12 mi. SE Dos Cabezos, 2 (UM); 1 mi. WSW Chiricahua National Monument, 5000 ft., 1 (MVZ); Portal, 4500 ft., 2 (USBS); Fairbank, 8 (3 AMNH; 5 CNHM); Mouth Pinery Canyon, 4 (USBS).

=New Mexico=: _Torrance County_: Gran Quivira, Mesa Jumanes, 6 (USBS). _Catron County_: Mangos Valley, 3 (USBS); Alma, 3 (USBS); Pleasanton, 7 (USBS). _Socorro County_: Gallina Mountains, 1 (USBS); 10 mi. NE Socorro, 2 (USBS); 3 mi. N Socorro, 3 (MVZ); Socorro, 1 (USBS); Range, 2 mi. SW Socorro, 4700 ft., 2 (MVZ); Lava Mesa; S Clyde, 4300 ft., 1 (MVZ); Dry Creek, 3 (USBS); San Augustine Plain, 12 mi. N Monica Springs, 2 (USBS). _Lincoln County_: Guyo Canyon, 40 mi. SE Corona, 1 (USBS); 4 mi. W Carrizozo, 2 (UM). _Grant County_: Gila, 5 (USBS); Cactus Flat, 20 mi. N Cliff, 3 (USBS); Cliff, Gila River, 4470 ft., 1 (USBS); Silver City, 2 (USBS); Redrock, 2 (USBS); 9 mi. N Faywood, 2 (USBS); Hachita, 1 (USBS); Dog Spring, 11 (USNM); Deer Creek, Culberson Ranch, 2 (USBS). _Sierra County_: Fairview, 6500 ft., 1 (USBS); Cuchillo, 4700 ft., 3 (USBS); Lake Valley, 5000 ft., 3 (USBS). _Otero County_: Tularosa, 5 (USBS); 10 mi. SW Tularosa, 2 (CNHM); Quartz Sands, SW Tularosa, 2 (MVZ); White Sands, 12 mi. W Alamogordo, 1 (MVZ); 2 mi. S Alamogordo, 2 (UM); 3 mi. S Alamogordo, 1 (UM); 5 mi. S Alamogordo, 1 (UM); 9 mi. SW Alamogordo, 1 (UM); 12 mi. SW Alamogordo, 2 (UM); 15 mi. SW Alamogordo, 1 (LACM); White Sands, 18 mi. SW Alamogordo, 7 (MVZ); 19 mi. SW Alamogordo, 3 (UM); White Sands National Monument, 24 (13 CNHM; 11 LACM); 1/2 mi. SW Escondido, 4000 ft., 2 (MVZ); Jarilla, 1 (USBS). _Hidalgo County_: 10 mi. NW Lordsburg, 6 (LACM); 4 mi. NW San Luis Pass, 5200 ft., Animas Valley, 5 (MVZ). _Luna County_: Deming, 11 (USBS). _Dona Ana County_: Garfield, 4 (USBS); 6 to 8 mi. NE Las Cruces, 1 (CAS); 15 mi. W Las Cruces, 1 (LACM); 11 mi. W Las Cruces, 2 (CAS); Las Cruces, 3 (USBS); Organ Mountains, near Globe Springs, 2 (USBS); Coe's Ranch, El Paso Road, 35 mi. N El Paso, Texas, 2 (USBS); 1/4 mi. N Strauss, 2 (CAS); 1 mi. E Strauss, 4100 ft., 7 (MVZ); 35 mi. W El Paso, Texas, 2 (USNM); 20 mi. W El Paso, Texas, 1 (USNM); 10 mi. W El Paso, Texas, 1 (USNM); Mexican Boundary, near monument 5, Lat. 31° 47'; Long. 30° 15', 13 (USNM). _Eddy County_: 3 mi. NW Carlsbad, 7 (MVZ); 2 mi. E Carlsbad, 1 (KU); Eddy, 10 (USBS).

=Texas=: _El Paso County_: 3 mi. NE City Limits, El Paso, 3764 ft., 15 (12 MVZ; 3 TCWC); El Paso, 3 (USBS); near El Paso, 7 (USNM). _Hudspeth County_: 1 mi. NW old Fort Hancock, 3900 ft., 3 (MVZ); Fort Hancock, 4 (USNM); 4 mi. NW Sierra Blanca, 1 (LACM). _Culberson County_: 35 mi. N Van Horn, 5 (TCWC); 30 mi. N Van Horn, 1 (TCWC); 16 mi. E Van Horn, 3 (TCWC); 16 mi. SE Van Horn, 5 (TCWC); Kent, 1 (USBS). _Reeves County_: 5 mi. E Toyahvale, 1 (USBS). _Jeff Davis County_: 14-1/2 mi. S Fort Davis, 2 (UM). _Presidio County_: 10 mi. NE Marfa, 1 (UM).

=Sonora=: Nogales, 2 (USNM); Santa Cruz, 4 (USNM); 5 mi. N Cananea, 4750 ft., 4 (MVZ); Alamo Wash, 35 mi. NW Magdalena, 5 (DRD); Sonora, 2 (AMNH).

=Chihuahua=: 4.3 mi. W Casas Grandes Viejo, 5000 ft., 8 (MVZ); 1.5