Rollin H. Baker

This file was derived from scanned images. With the exception of two typographical errors that were corrected, removal of an annotation to Figure 1, and rejoining the text which was split by the tables in the printed version, the original text and copies of the included illustrations are presented.

Typographical Errors Corrected:

   Page 603, Paragraph 2: subpecies => subspecies

   Page 607, Paragraph 2: Aquanaval => Aguanaval

The plateau pocket gopher, Cratogeomys castanops, inhabits open lands from southeastern Colorado southward onto the Mexican Plateau as far south as southern San Luis PotosÍ and southeastern Zacatecas and southeastward to the Coastal Plain of northern Tamaulipas. This species occurs at elevations from as low as 26 feet at Matamoras in Tamaulipas to as high as 8700 feet in valleys of south-eastern Coahuila. In 1934, Nelson and Goldman (Proc. Biol. Soc. Washington, 47:135-154, June 13, 1934) revised the genus Cratogeomys and decided that six subspecies of C. castanops occurred in Coahuila. In the present account, we describe four previously unknown subspecies from Coahuila, exclude from the state two others recorded from there by Nelson and Goldman, and show that three others named previously from adjacent Mexican states do occur in Coahuila. This makes eleven subspecies now known from that state. From Coahuila Nelson and Goldman had 35 study specimens of C. castanops from seven localities and we have had 234 specimens from 63 localities. Consequently we have been able to define with greater certainty, than formerly was possible, the geographic distribution of C. castanops in this Mexican state and similarly analyze more completely the geographic variation.

Coahuila is near the center of the geographic range of C. castanops. The occurrence of 11 subspecies within the state seems to be the result of partial or perhaps, in some cases, total isolation of populations of C. castanops because of the highly dissected topography and the variability of the soil. Cratogeomys castanops is a sedentary animal preferring open plains mantled by suitable soils, preferably sandy in texture, in which the animals can dig their elaborate underground systems of runways. Thin soils of hard texture and rocky soils do not offer optimum habitat for C. castanops, and the animals usually are absent or uncommon in such situations. Desert mountains with their thin rocky soils, elevated passes, perpendicular rocky cliffs, and stands of oaks and conifers at higher elevations present impassable barriers for pocket gophers of this species. The RÍo Grande, bordering Coahuila to the north, in many places flowing through steep-walled caÑons, also seems to be a barrier that this fossorial rodent does not cross; distinct subspecies occur on the two sides of the river directly opposite each other (also see Nelson and Goldman, op. cit.: 143). Smaller streams, such as the RÍo Salado, RÍo Nazas and RÍo Salinas, seem to be unimportant barriers to the passage of these pocket gophers. The food supply of C. castanops seems adequate in most situations and consequently food is unimportant in governing the distribution of this species. Principal foods of C. castanops are fleshy tuberous roots of well-distributed desert shrubs, but in the valleys of the high mountains of southeastern Coahuila, where desert shrubs are absent, roots and leaves of low-growing forbs are eaten.

Three distinct habitats for C. castanops occur in Coahuila. The state is crossed by a series of mostly impassable, mountainous ridges beginning at the northwestern boundary at the CaÑon de Boquillas on the RÍo Grande and extending southeastward to the east-central border. This divides Coahuila into a more humid and less elevated northeastern area which is an inland extension westward of the Coastal Plain and a more arid and higher western and southern area which is a part of the "Mesa del Norte" of the Mexican Plateau. In the extreme southeast the still higher elevated plains and intermontane valleys within the Sierra Madre Oriental afford a third habitat for populations of this species. The subspecies of these pocket gophers found in any one of these three habitats show greater affinity to each other than they do to any subspecies found in the other habitats.

Generally speaking, populations of C. castanops from northeastern Coahuila are related, as a group, in color and cranial features. Partial isolation of subspecies in this area results chiefly from discontinuity of suitable soils rather than from topography. These pocket gophers occur most commonly in the deep, sandy soils which are found along streams, especially where farm lands are irrigated. In western and southern Coahuila, mountains extending in both north-south and east-west directions act as partial barriers to the passage of C. castanops. Within this large area, pocket gophers occur in desert basins many of which are enclosed on two or more sides by mountains. Even so, with the exception of the smaller C. c. consitus of northwestern Coahuila, all known subspecies occurring at lower elevations in the western and southern part of the state show close relationships in color and cranial features. Those subspecies in the higher parts of southeastern Coahuila by their small size and dark color reflect to a high degree their isolation in an elevated habitat.

Males of C. castanops differ greatly from females of equal age; consequently animals of the same sex, as well as of the same age, are used herein for taxonomic comparisons. Since, of any given age-group, females show less individual variation than do males, we have relied more on the characteristics of the females in this taxonomic study. Only specimens taken at approximately the same times of the year have been compared for color of pelage. Capitalized color terms are those of Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912. Specimens made available through the courtesy of the authorities of the Biological Surveys Collection of the United States National Museum are indicated in the accounts of subspecies as BSC; other specimens listed are in the collection of the University of Kansas Museum of Natural History. Assistance with field work is acknowledged from the Kansas University Endowment Association and the National Science Foundation.

In any one of the lists of "Specimens examined" beyond, the order of arrangement of the localities is from north to south. Those localities listed in Roman type are represented on the distribution map (Figure 1) by blacked-in circles. Each of several circles covers two or more localities because the localities are close together. In any such instance the northernmost place is listed in Roman type and the names of the other places follow in Italic type. Measurements in millimeters are given in table 1 for females and in table 2 for males.

Distribution.--Extreme northern Coahuila, east and north of the SerranÍas del Burro (see fig. 1).

Diagnosis.--Previously known from only one specimen, a subadult female, this subspecies has not been well diagnosed. At hand we have five near topotypes of convexus (including two adult females and one adult male) and specimens assignable to this subspecies from several other localities. This subspecies may be characterized as follows: Size medium (see tables 1 and 2); dorsal profile of skull convex in females and flat, especially posteriorly, in males; zygomata weakly constructed and not widely flaring; mastoid and tympanic bullae inflated; nasals short; rostrum broad and short; maxillary teeth large.

Comparisons.--From topotypes of Cratogeomys castanops angusticeps Nelson and Goldman, found to the north and east across the RÍo Grande in Texas, convexus differs in: Body larger; upper parts more reddish, especially on sides; skull with zygomata less heavy, nasals broader, pterygoids smaller, maxillary teeth larger. For comparisons of convexus with the subspecies of C. castanops found to the west, south and southeast, see accounts of the subspecies to follow.

Specimens examined.--Total, 14, all from Coahuila: RÍo Grande, 17 mi. S Dryden, Terrell Co., Texas, 6; RÍo Grande, opposite Samuels, Val Verde Co., Texas, 1 (BSC); Villa AcuÑa, 5; CaÑon del Cochino, 21 mi. E and 16 mi. N Piedra Blanca, 1; 11 mi. W Hda. San Miguel, 1.

Type.--Female, adult, skin and skull, No. 48498, Univ. Kansas Mus. Nat. Hist., 2 mi. S and 6-1/2 mi. E Nava, 810 ft., Coahuila; 16 June 1952; obtained by Robert J. Russell, original number 276.

Distribution.--Desert lowlands of northeastern Coahuila, from the RÍo Grande to as far southwestward as the RÍo Sabinas (see fig. 1).

Diagnosis.--Body medium for the species (see tables 1 and 2); tail long; hind foot small; upper parts Light Ochraceous-Buff (in summer pelage) and Orange-Buff (in winter pelage), bases of hairs Plumbeous; underparts white to pale buffy; skull small, broad and slightly convex in dorsal outline; zygomata widely flaring; palate short; rostrum short; nasals short; mastoid and tympanic bullae inflated; basioccipital with lateral edges parallel; maxillary teeth small.

Comparisons.--From Cratogeomys castanops convexus, found to the north, bullatus differs in: Hind foot shorter; skull much broader in relation to length; rostrum narrower but, relative to length of skull, wider; tympanic bullae slightly more inflated; incisors and maxillary teeth smaller. From topotypes of Cratogeomys castanops angusticeps, found across the RÍo Grande and upstream from localities where bullatus is known to occur, bullatus differs in: Body slightly smaller; color paler, especially on sides; skull shorter and broader; rostrum shorter and broader; nasals shorter; mastoid and tympanic bullae more inflated; maxillary teeth smaller. For comparisons of bullatus with the subspecies of C. castanops found to the west and south, see accounts of the subspecies to follow.

Specimens examined.--Total, 24, from: 2 mi. S and 6-1/2 mi. E Nava, 810 ft., 2; 2 mi. S and 12 mi. E Nava, 800 ft., 1; 3 mi. S and 12 mi. E Nava, 800 ft., 4; 29 mi. N and 6 mi. E Sabinas, 5; 10 mi. E Hacienda La Mariposa, 2000 ft., 1; La Gacha [= La Concha], 1600 ft., 8; 8 mi. S and 8 mi. E Hacienda La Mariposa, 1900 ft., 1; 9 mi. S and 11 mi. E Sabinas, 1050 ft., 2.

Type.--Female, adult, skin and skull, No. 34589, Univ. Kansas Mus. Nat. Hist., Don Martin, 800 ft., Coahuila; 19 August 1949; obtained by W. Kim Clark, original number 1034.

Distribution.--Extreme northeastern Coahuila from the vicinity of Presa Don Martin southward into northwestern Neuvo LeÓn in the valley of the RÍo Salado and its tributaries at least as far south as the vicinity of Vallecillo (see fig. 1).

Diagnosis.--Body large for species (see tables 1 and 2); hind foot short; upper parts Apricot Buff (in fresh summer pelage) and Salmon-Buff strongly mixed with black (in fresh winter pelage); underparts Light Ochraceous-Buff; skull large, especially in females, and broad; zygomatic arches widely flaring; palate long; rostrum broad; nasals long; mastoid and tympanic bullae not conspicuously inflated; incisors narrow; maxillary teeth large.

Comparisons.--From Cratogeomys castanops bullatus found to the north, ustulatus differs in: Body larger; tail shorter; upper parts darker, more rufous and less buffy; skull larger, especially in palate, nasals, and rostrum; zygomata more widely flaring; tympanic bullae less inflated; incisors slightly larger; maxillary teeth larger. From topotypes of Cratogeomys castanops tamaulipensis found to the southeast, ustulatus differs in: Body larger; upper parts, in winter pelage, darker, more rufous and less buffy; underparts paler; skull larger, especially in palate, rostrum and nasals; zygomata more widely flaring; tympanic bullae more inflated; pterygoids larger; basioccipital narrower, its sides parallel instead of convex; maxillary teeth smaller. From Cratogeomys castanops subsimus, found to the southwest, ustulatus differs in: Tail shorter; hind foot smaller; upper parts darker, more rufous and less pinkish-buff; skull shorter; zygomata less widely flaring; palate shorter; rostrum averaging slightly narrower; nasals shorter; incisors narrower; maxillary teeth slightly smaller. For comparison of ustulatus with the subspecies of C. castanops to the southwest, see account of that subspecies to follow.

Specimens examined.--Total, 10, from: Don Martin, 800 ft., 5; base of Don Martin Dam, 2; 2 mi. SE Don Martin Dam, along RÍo Salado, 2; 5 mi. SE Don Martin, 1.

Records from Nuevo LeÓn.--Total, 14, from: 9 mi. N and 2 mi. W Anahuac [= RodrÍques], 1; 4 mi. N and 1 mi. W Anahuac [= RodrÍques], 5; 3 mi. N Lampazos, 4; 1 mi. N Vallecillo, 1000 ft., 1; Vallecillo, 20 mi. S RÍo Salado, 1000 ft., 3.

Type.--Female, adult, skin and skull; No. 56603, Univ. Kansas Mus. Nat. Hist.; Hermanas, 1205 ft., Coahuila; 5 December 1953; obtained by Robert W. Dickerman, original number 2051.

Distribution.--Arid plains and broad intermontane valleys of east-central Coahuila (see fig. 1).

Diagnosis.--Body largest for the species (see table 1); tail long; hind foot large; upper parts in winter pelage Ochraceous-Buff, in summer pelage Antimony Yellow; underparts Pale Ochraceous-Buff; skull medium in size, broad; zygomata moderately flaring; palate medium in length; rostrum broad; nasals moderately long; maxillary teeth small.

Comparisons.--From Cratogeomy castanops ustulatus, found to the east, jucundus differs in: Body larger; tail longer; hind foot larger; upper parts paler, more ochraceous and less rufous; skull averaging smaller; zygomata slightly less expanded laterally; palate and nasals shorter; squamosal breadth less; mastoid bullae less inflated, especially in females; rostrum slightly narrower; maxillary tooth-row shorter. From topotypes of Cratogeomys castanops tamaulipensis, found to the southeast, jucundus differs in: Body larger; tail longer; hind foot smaller; upper parts, in winter pelage, paler, more ochraceous and less rufous; skull larger; zygomata more widely flaring; palate longer; rostrum broader; tympanic bullae more inflated; basioccipital with sides parallel instead of convex; maxillary teeth smaller. From Cratogeomy castanops excelsus, found to the southwest, jucundus differs in: Body larger; hind foot averaging larger; upper parts darker, more ochraceous, and less buffy; underparts darker, more buffy and less whitish; skull slightly smaller; zygomata less widely flaring, especially in females; palate shorter; nasals shorter; squamosal breadth less; mastoid bullae more inflated; incisors narrower. From Cratogeomys castanops subsimus, found to the south, jucundus differs in: Body larger; tail shorter; hind foot shorter; upper parts paler, more ochraceous and less yellowish; skull smaller; zygomata less widely expanded laterally; palate and nasals shorter; rostrum narrower; squamosal breadth less; maxillary tooth-row shorter. From Cratogeomys castanops bullatus, found to the north, jucundus differs in: Body larger; tail averaging longer; hind foot larger; color of upper parts more ochraceous and less rufous; underparts darker, more buffy and less whitish; skull larger, especially in length, in width across zygomata, in lengths of palate, rostrum and nasals; mastoid and tympanic bullae less inflated; squamosal breadth greater.

Specimens examined.--Total, 19, from: Hermanas, 1205 ft., 9; 1 mi. S Hermanas, 2; 1 mi. N and 13 mi. E Cuatro CiÉnegas, 2; 5 mi. N and 2 mi. W Monclova, 1; 2 mi. N and 1 mi. E Monclova, 1; Monclova, 2 (BSC); Hisachalo [= Huisachalo], 2.

Type.--Female, adult, skin and skull; No. 56614, Univ. Kansas Mus. Nat. Hist.; 1.5 mi. NW Ocampo, 3300 ft., Coahuila; 16 December 1953; obtained by Robert W. Dickerman, original number 2164.

Distribution.--Desert plains of north-central Coahuila, surrounded for the most part by higher mountainous country (see fig. 1).

Diagnosis.--Body large for species (see tables 1 and 2); tail short; hind foot large; upper parts Ochraceous-Buff (in summer pelage) and Orange-Buff (in fresh winter pelage); underparts Pale Ochraceous-Salmon; skull medium in size and narrow; zygomata narrow; rostrum narrow; palate short; nasals medium in length; basioccipital small and narrow; mastoid bullae not greatly inflated; tympanic bullae inflated; incisors small; maxillary teeth small.

Comparisons.--From Cratogeomys castanops jucundus, found beyond the mountains to the southeast, sordidulus differs in: Body smaller; tail shorter; hind foot slightly smaller; upper parts darker, more ochraceous and less yellowish, with plumbeous bases of hairs more conspicuous; underparts darker, more buffy and less whitish; skull slightly shorter, more nearly flat, and narrower; zygomata less widely flaring; rostrum narrower; mastoid bullae less inflated; incisors and maxillary teeth slightly smaller. From Cratogeomys castanops excelsus, found to the south and southwest, sordidulus differs in: Body slightly smaller; tail shorter; hind foot slightly larger; upper parts darker, more ochraceous and less pinkish-buff; underparts darker, more buffy and less whitish; skull smaller and narrower; zygomata less widely flaring; sides more nearly parallel and not expanded anteriorly; palate shorter; rostrum narrower and, in relation to greatest length of skull, longer; tympanic bullae slightly more inflated; incisors and maxillary teeth smaller. From Cratogeomys castanops consitus, found to the north and west, sordidulus differs in: Body larger; hind foot larger; upper parts paler, more ochraceous and less rufous; skull decidedly larger and wider; zygomata more widely flaring; palate and nasals longer; rostrum broader; mastoid bullae and tympanic bullae larger; maxillary teeth smaller. From topotypes of Cratogeomys castanops clarkii (Baird), found to the northwest, sordidulus differs in: Body larger; tail shorter; upper parts, in winter pelage, paler, more ochraceous and less dark-rufous; skull slightly smaller and narrower; rostrum narrower; nasals slightly shorter; sides of basioccipital more nearly parallel instead of wedge-shaped; mastoid bullae less inflated; incisor and maxillary teeth smaller. From Cratogeomys castanops convexus, found to the northeast, sordidulus differs in: Body larger; tail shorter; upper parts slightly darker, more ochraceous and less buffy; skull narrower; zygomata more nearly parallel and less expanded anteriorly; rostrum narrower and longer; nasals longer; squamosal breadth greater; mastoid bullae less inflated; maxillary teeth smaller. From Cratogeomys castanops bullatus, found to the east, sordidulus differs in: Body larger; hind foot larger; upper parts darker, more ochraceous and less buffy; skull larger in all respects; zygomata more widely flaring; tympanic bullae less inflated; maxillary teeth larger.

Specimens examined.--Total, 13, from: 50 mi. N and 20 mi. W Ocampo, 4150 ft., 1; 18 mi. S and 14 mi. E Tanque Alvarez, 4000 ft., 4; 1-1/2 mi. NW Ocampo, 3300 ft., 6; Ocampo, 1; 5 mi. N and 19 mi. W Cuatro CiÉnegas, 3250 ft., 1.

Distribution.--Arid high plains from central Chihuahua, east and southeast at least into northwestern Coahuila (see fig. 1).

Comparisons.--From Cratogeomys castanops lacrimalis Nelson and Goldman, specimens from Boquillas and Marathon north of the RÍo Grande in Texas, consitus differs in: Body smaller; tail and hind foot shorter; upper parts paler, more light buffy and less rufous; underparts paler, light buffy instead of dark buffy; skull decidedly smaller; zygomata slightly less widely flaring; palate especially shorter; rostrum narrower; squamosal breadth less; incisors smaller. From topotypes of Cratogeomys castanops clarkii, found to the north along the RÍo Grande, consitus differs in: Body smaller; tail and hind foot shorter; upper parts paler, more buffy and less rufous; skull markedly smaller, especially in palate and nasals; zygomata less widely flaring; tympanic bullae more inflated; mastoid bullae less inflated; basioccipital parallel-sided as opposed to wedge-shaped. From Cratogeomys castanops convexus, found to the east, consitus differs in: Body smaller; tail and hind foot shorter; upper parts paler, more buffy and less ochraceous; underparts paler, white or light buffy instead of pale ochraceous; skull smaller; zygomata less widely flaring; palate shorter; rostrum decidedly narrower and, relative to length of skull, longer; squamosal breadth less; incisors smaller. From Cratogeomys castanops excelsus, found to the south, consitus differs in: Size smaller; tail and hind foot shorter; upper parts darker, more rufous and less pinkish-buff; skull conspicuously smaller, especially in palate, rostrum, and nasals; zygomata less widely flaring; mastoid bullae and tympanic bullae more inflated; incisors smaller; maxillary teeth relatively larger. For comparison of consitus with Cratogeomys castanops sordidulus, see previous account.

Specimens examined.--Total, 8, from: 3 mi. N and 9 mi. E El Pino, 1; 6 mi. E Jaco, Chihuahua, in Coahuila, 6; 3 mi. NE Sierra Mojada, 1.

Distribution.--Desert plains of southwestern Coahuila and northeastern Durango (see fig. 1).

Comparisons.--Cratogeomys castanops excelsus is characterized by large size and pale color; it is the palest subspecies of C. castanops. Of adjacent subspecies, excelsus most closely resembles C. c. subsimus which occurs to the east and resembles least C. c. consitus, which occurs to the northwest.

From Cratogeomys castanops subsimus, found to the east, excelsus differs in: Body averaging slightly larger; tail and hind foot shorter; upper parts paler, more light buffy and less yellowish; skull smaller; palate especially shorter; rostrum narrower; nasals shorter; incisors slightly smaller; maxillary tooth-row shorter. Compared with topotypes of C. c. goldmani, found to the south, excelsus differs in: Body larger; hind foot smaller; upper parts in winter pelage paler, more buffy and less rufous; skull larger; zygomata more widely flaring; rostrum broader; nasals shorter; tympanic bullae larger and more inflated; maxillary teeth larger.

Specimens of excelsus from the vicinity of TorreÓn, in southwestern Coahuila, are slightly smaller in cranial dimensions than more typical examples of the subspecies. In small size, at least, these specimens show some resemblance to goldmani to the south. The range of excelsus approaches that of C. c. consitus in west-central Coahuila (see fig. 1), but no evidence of intergradation between these two subspecies could be ascertained. For comparison of excelsus with consitus, see account of the latter.

Specimens examined.--Total, 33, from: 8 mi. E and 2 mi. S Americanos, 3500 ft., 3; 4 mi. N Acatita, 3600 ft., 9; 20 mi. S El Hundido, 1; San Pedro, 2 (BSC); 1 mi. SW San Pedro de las Colonias, 3700 ft., 4; 10 mi. N and 11 mi. W San Lorenzo, 2; 2 mi. E TorreÓn, 12.

Distribution.--Desert plains and lower foothills of mountains in south-central Coahuila (see fig. 1).

Comparisons.--From Cratogeomys castanops goldmani, found to the southwest, subsimus differs in: Body larger; hind foot larger; upper parts paler, more yellowish and less rufous; skull larger and rougher, having more prominent ridges and crests and deeper fossae for attachment of muscles; zygomata more widely flaring; palate longer; rostrum broader; nasals longer; squamosal breadth greater; maxillary teeth larger. From C. c. subnubilus, found to the south, subsimus differs in: Body larger; tail and hind foot shorter; upper parts paler, more yellowish-buff and less blackish; skull decidedly larger in all respects. From C. c. planifrons, found at higher elevations to the southeast, subsimus differs in the same respects as subsimus differs from subnubilus. For comparisons between subsimus and subspecies to the west, north and northeast, see accounts above.

Specimens examined.--Total, 22, from: 3 mi. S and 3 mi. E Muralla, 3800 ft., 3; 2 mi. N Santa Cruz, 2; 21 mi. S and 11 mi. E Australia, 4400 ft., 6; Jaral, 3860 ft., 4 (BSC); Hacienda El Tulillo, 5 km. S Hipolito, 2; 17 mi. N and 8 mi. W Saltillo, 5200 ft., 1; 3 mi. N and 5 mi. W La Rosa, 3600 ft., 1; 12 mi. N and 10 mi. E Parras, 5000 ft., 1; N foot Sierra Guadalupe, 9 mi. S and 5 mi. W General Cepeda, 6200 ft., 1; N foot Sierra Guadalupe, 10 mi. S and 5 mi. W General Cepeda, 6500 ft., 1.

Distribution.--Plains of northeastern Zacatecas, northward into extreme southwestern Coahuila (see fig. 1).

Comparisons.--Compared with Cratogeomys castanops subnubilus, found to the east, goldmani differs in: Body larger, tail and hind foot longer; color paler, more rufous and less blackish; skull larger; zygomata more widely flaring; palate larger; rostrum broader; nasals longer; maxillary teeth larger. Compared with Cratogeomys castanops rubellus Nelson and Goldman, found to the southeast, goldmani differs in: Body and skull smaller; zygomata less widely flaring; palate shorter; rostrum narrower; maxillary teeth smaller.

Remarks.--Records of goldmani given here extend the known range of this subspecies northward into southwestern Coahuila. Specimens assigned to this subspecies from Coahuila compare favorably with topotypes of goldmani (see tables 1 and 2) but are slightly paler, and in this respect show some relationship to excelsus. The ranges of these two subspecies however, are partly isolated by mountainous country in southern Coahuila.

Specimens examined.--Total, 6, from: W foot Pico de Jimulco, 4600 ft., 1; Valley RÍo Aguanaval, 1 mi. S Jimulco, 4; 1-1/2 mi. N Parras, 1.

Distribution.--Intermontane valleys and plains of southeastern Coahuila and probably adjacent parts of Zacatecas, San Luis PotosÍ and Nuevo LeÓn (see fig. 1).

Comparisons.--Cratogeomys castanops subnubilus needs close comparison only with Cratogeomys castanops planifrons, found to the east and from which subnubilus differs in: Body, hind foot and skull smaller; upper parts, in summer pelage, paler, more rufous-buff and less dark russet; underparts paler, more whitish and less blackish; hairs of hind foot reddish rather than blackish; zygomata more widely flaring; palate shorter, especially in females; rostrum broader, especially in females; nasals slightly smaller; squamosal breadth greater; incisors narrower, especially in males; maxillary teeth smaller. From Cratogeomys castanops rubellus Nelson and Goldman, found to the south in San Luis PotosÍ, subnubilus differs in: Body, hind foot and all parts of skull smaller; upper parts and underparts darker, more blackish and less rufous.

Specimens examined.--Total, 31, from: 1 mi. N Agua Nueva, 5500 ft., 1; Domingo CaÑon, Sierra Guadalupe, 6700 ft., 11 mi. S and 4 mi. W General Cepeda, 1; Carneros, 6800 ft., 6 (BSC); 1 mi. S Carneros, 6000 ft., 4; 2 mi. W San Miguel, 5500 ft., 3; 8 mi. N La Ventura, 6000 ft., 10; La Ventura, 5600 ft, 6 (BSC).

Distribution.--Elevated montane valleys of Sierra Madre Oriental of extreme southeastern Coahuila, south and east into southwestern Nuevo LeÓn and Western Tamaulipas (see fig. 1).

Specimens examined.--Total, 50, from: 4 mi. S and 6 mi. E Saltillo, 7500 ft, 7; 7 mi. S and 4 mi. E Bella Union, 7200 ft., 14; 12 mi. W San Antonio de las Alazanas, 16; 12 mi. S and 2 mi. E Arteaga, 7500 ft., 11; 2 mi. E and 2 mi. N San Antonio de las Alazanas, 8700 ft, 2.

Transmitted August 23, 1954.