Intergradation is noted with _D. o. ordii_, _D. o. longipes_, _D. o. montanus_ and _D. o. richardsoni_. Among named races _D. o. medius_ shows closest affinities with _D. o. richardsoni_ but the two are easily separable. The northwestern extremity of the range of _D. o. medius_ is an area of intergradation in which no specimens are clearly of one subspecies or the other. In specimens from 5 miles east of Abiquiu, New Mexico, three-way intergradation occurs. These animals are like _D. o. medius_ in size, _D. o. longipes_ in color and their cranial proportions are as in _D. o. montanus_. At Deer Creek, New Mexico, and at Monahans, Texas, the animals show intergradation in size of body and agree with _D. o. ordii_ in cranial proportions. In specimens from 6 miles southwest of Muleshoe, Texas, intergradation with _D. o. richardsoni_ in the shape of the skull and width of the rostrum is noted. In the sum total of characters studied, however, these specimens are referable to _D. o. medius_. _Specimens examined._--Total, 129, distributed as follows: =New Mexico=: _Rio Arriba County_: 2 mi. SE El Rito, 2 (KU); Rio Alamosa, 15 mi. N Ojo Caliente, 1 (USBS); 6 mi. E Abiquiu, 4 (USBS); Rinconada, 5 (USBS); Espanola, 6 (USBS). _Sandoval County_: 12 mi. NW Alameda, 5500 ft., 3 (MVZ). _Santa Fe County_: Seton's Ranch, near Santa Fe, 1 (USBS); 8 mi. SW Santa Fe, 8 (KU); San Pedro, 3 (USBS). _San Miguel County_: Pecos, 2 (USBS); 3 mi. S Pecos, 2 (USBS); Rowe, 6 (LACM). _Bernallilo County_: Bear Canyon, Sandia Mountains, 7 (USBS); Pajarito, 3 (MVZ). _Guadalupe County_: Santa Rosa, 10 (USBS). _Lincoln County_: 44 mi. NW Roswell, 5 (MVZ). _De Baca County_: 8 mi. N Fort Sumner, 9 (USBS). _Roosevelt County_: Kenna, 4 (LACM). _Curry County_: 4 mi. W and 2-3/4 mi. N Clovis, 1 (MVZ). _Chaves County_: 40 mi. N Roswell, 2 (USBS); 35 mi. N Roswell, 2 (USBS); 15 mi. NE Roswell, 8 (LACM); Stinking Springs Lake, 3 (USBS). =Texas=: _Bailey County_: 6 mi. SW Muleshoe, 5 (UM); 9 mi. SW Muleshoe, 2 (UM). _Garza County_: 7 mi. E Post, 5 (UM). _Martin County_: Stanton, 4 (USBS). _Howard County_: 6 mi. NE Coahoma, 7 (UM); 1 mi. S Coahoma, 1 (UM); 5 mi. W Big Springs, 2400 ft., 1 (MVZ). _Mitchell County_: Colorado, 5 (USBS). _Winkler County_: 20 mi. N Monahans, 1 (USBS). _Ward County_: Monahans, 1 (USBS). =Dipodomys ordii obscurus= (Allen) _Perodipus obscurus_ Allen, Bull. Amer. Mus. Nat. Hist., 19:603, November 12, 1903. _Dipodomys ordii obscurus_, Grinnell, Journ. Mamm., 2:96, May 2, 1921. _Type._--Male, adult, no. 20957, Amer. Mus. Nat. Hist.; Rio Sestin, northwestern Durango, Mexico; obtained on April 13, 1903, by J. H. Batty. (Type not seen.) _Range._--Northwestern and northern Durango, Mexico; marginal localities are: Rosario, Rio Sestin, Mt. San Gabriel, Rio del Bocas, Villa Ocampo.