Part 2

Judging from the description and photograph of mexicana in Goldman's revision of the genus Neotoma (N. Amer. Fauna, 31: 54-56, Pl. IV, 19 October 1910), scopulorum differs from N. m. mexicana in: larger skull; longer nasals and dorsal branches of premaxillae; more posterior interorbital constriction (supraorbital ridges more concave laterally); wider upper incisors; and larger molars.

Measurements.--Mean and extreme measurements in millimeters of 6 males and 5 females from 3 mi. NW Higbee and the vicinity of Two Buttes are, respectively, as follows: total length, 357 (345-368), 345 (310-379); length of tail, 147 (140-158), 159 (138-178); length of hind foot, 35 (32-38), 36.4 (35-38); length of ear, from notch, 25.5 (25-26), 25.7 (25-27); weight (in grams), 234 (213-253), 206 (161-246); basilar length, 37.9 (36.8-38.9), 36.2 (34.5-38.6); length of nasals, 19.0 (18.2-20.0), 17.9 (16.4-19.6); zygomatic breadth, 23.9 (23.0-24.5), 23.3 (22.3-24.0); interorbital breadth, 5.3 (4.9-5.6), 5.1 (5.0-5.3); breadth of rostrum, 7.2 (6.8-7.7), 6.8 (6.7-6.9); diastema, 12.8 (12.3-13.3), 12.2 (11.1-13.7); alveolar length of maxillary tooth-row, 9.5 (9.2-9.8), 9.4 (9.0-9.7); length of incisive foramina, 9.7 (9.2-10.2), 9.2 (8.6-10.2); length of palatal bridge, 8.8 (8.4-9.2), 8.5 (8.0-8.9).

Measurements of the type.--Total length, 348; length of tail, 143; length of hind foot, 35; length of ear, from notch, 25; weight (in grams), 230; basilar length, 38.1; length of nasals, 18.8; zygomatic breadth, 24.2; interorbital constriction, 5.5; breadth of rostrum, 7.2; diastema, 13.0; alveolar length of maxillary tooth-row, 9.2; length of incisive foramina, 9.7; length of palatal bridge, 8.9.

Remarks.--The large size and distinctive cranial characters of N. m. scopulorum are fairly constant in the northeastern part of its range, but there is a wide range of variation in color. The only two skins from the type locality differ markedly in color. Both specimens (the type and KU 37138, adult male) were collected on 16 May 1950 and are in moderately worn pelage. The upper parts of the holotype are much more yellowish than in KU 37138, and are even lighter buff than adults in unworn pelage from Two Buttes. The underparts of the holotype are more extensively white than in almost any other specimen seen of Neotoma mexicana. The basal gray coloration, where it is present along the sides of the venter, forms only a narrow intermediate color band extending not more than one third the length of the hairs. An extensive area of the throat, breast, axillae, median belly, and inguinal region is covered by hairs pure white to the skin. The dark line around the mouth is present, as usual for the species. The upper parts of KU 37138 are like those of the adult in worn pelage from Two Buttes peak, described above; the underparts have only small patches of pure white fur on the throat and inguinal region, being elsewhere gray at the base of the fur, as is usual for the species.

The molars of the type specimen are in an advanced state of wear, having the pattern of the enamel folds still discernible but the depth of remaining enamel slight. A large alveolar abscess surrounds the abnormal left M1. There are two, much worn, peglike fragments of the tooth projecting slightly from an ovoid alveolar cavity 5.1 mm. long and 4.3 mm. wide. As a result of the reduction of wear on the opposing m1, the crown of m1 is much less worn than those of the other lower molars and projects 0.8 mm. above the occlusal level of the two posterior molars. A few barbed cactus glochids (bristles) are inbedded in the cavity around the base of the molar remnants. Although glochids are of rather frequent and normal occurrence between the teeth of Neotoma albigula and N. micropus, they are not so commonly found in N. mexicana and possibly induced the alveolar infection in this individual.

In addition to the skins in unworn and worn pelages already described from Two Buttes, an extremely dark specimen is at hand from Two Buttes peak, taken on 9 May 1950. This specimen (KU 37141 [Female]) is an adult in moderately worn pelage. The back is dark brownish gray (Taupe, 16 A 6), the sides lighter (a shade lighter than Beaver, 15 A 6). The entire underparts are washed with reddish buff (Grain, 11 B 5) over the gray basal coloration, with a patch of white only in the genital region. The dark eye ring and dark line around the mouth are heavier than usual. The underside of the tail is light gray. The white hind feet are sharply set off from the dark gray ankles.

Each of four skulls from Regnier (three adults and one subadult) differs from skulls from Two Buttes in having a longer interparietal with a posterior angle. The skins of five adults collected in December at Trinchera are less richly colored on the sides than skins from Two Buttes and look more nearly like topotypes of N. m. fallax. The skull of one of the five from Trinchera differs from skulls from Two Buttes in much narrower nasals anteriorly, narrower rostrum, much narrower upper incisors, and smaller zygomatic breadth, these characters being as in fallax.

Four adults and one subadult from Trinidad are intergrades between N. m. scopulorum and N. m. fallax, perhaps more nearly resembling the former. In pelage they are indistinguishable from specimens of fallax from Gold Hill (the type locality), less buff than most individuals of scopulorum from Otero, Prowers, and Baca counties. The skulls of the three fully mature adults are large with a wide zygomatic breadth, large rostrum, and large upper incisors as in scopulorum; but the upper molars are small and the bullae are rather small and narrow as in fallax. In the degree of arching at the base of the rostrum, the shape of the frontal, the shape of the interparietal, and the size of the upper molars, the specimens from Trinidad are intermediate. It seems to me best to refer them to scopulorum.

Two first-year adults from Fisher Peak and Long Cañon are indistinguishable from topotypes of fallax of similar age and also resemble a young adult and a subadult from Trinidad, but all are insufficiently mature to show subspecific characters distinctly. Until adequate series are available from southwestern Las Animas County it seems best to regard all specimens from the three localities as representatives of a single uniform population which is intermediate between fallax and scopulorum but more nearly like the latter. Unfortunately no other specimens are available from the foothill zone south of the Arkansas River where morphological intergradation and ecological transition between fallax and scopulorum might reasonably be expected to occur.

Three specimens from the north side of the Arkansas River, about 26 miles below Canon City, Pueblo County, are like fallax in size, dorsal profile of the skull, and shape of the interorbital constriction; but they approach scopulorum in shape of the interparietal, size of the rostrum, and size of the molars. They are intergrades referrable to fallax.

Neotoma mexicana was first reported from Oklahoma by W. Frank Blair in 1939 (Amer. Midl. Nat., 22:126) who referred a specimen from Tesequite Canyon, Cimarron County, to N. m. fallax. I have seen one specimen (MZ 80469) from Tesequite Canyon and refer it to scopulorum.

Of scopulorum, each of eight skulls, of the 28 skulls examined, has an anteroexternal enamel fold on the m3 and one (BSC 35222/47487 ) has an anterointernal fold on the m3. Of the other 19 mandibles, a few are too old to show such a fold, which tends to be obliterated with wear in later age, and the others lack the fold.

Two other wood rats (N. albigula warreni and N. micropus canescens) occur at many of the same localities as N. m. scopulorum. The dens of scopulorum almost always are situated among rocks, but the dens of warreni and canescens are in a variety of other situations as well as among rocks. Houses of sticks or cactus joints piled up around the base of a juniper (Juniperus monosperma), thicket of skunkbush (Rhus trilobata), clump of soapweed (Yucca glauca) or tree cactus (Opuntia arborescens) have been found to shelter only N. a. warreni or N. micropus canescens. When these wood rats are associated with scopulorum among the rocks, their dens can be recognized by the compact midden of innumerable cactus spines. The dens of scopulorum have only a few loosely scattered spine areoles or none at all.

I am grateful to the officials of the following institutions for permission to examine specimens from the collections under their care: Denver Museum of Natural History; Biological Survey Collection, U. S. Fish and Wildlife Service; American Museum of Natural History; Museum of Vertebrate Zoology, University of California; Museum of Zoology, University of Michigan. The drawings of the skulls were made by Victor Hogg.

Specimens examined.--Total 66, distributed as follows:

#Colorado.# Baca County: "Furnace Canyon" [= Furnish Canyon], 1 (DMNH); Regnier, 4500 ± ft., 4 (2 DMNH, 2 KU); Two Buttes Reservoir, 4200 ± ft., 5 (3 DMNH, 2 KU). Las Animas County: Fisher Peak, "about 8000 ft." [6 mi. SE Trinidad], 1 (BSC); Long Cañon (near Martinsen), 1 (BSC); Mesa de Maya, 1 (MZ); 9 mi. W jct. Purgatory [= Purgatoire] & Chaquaqua [= Chacuaco] rivers ("Red Rock Canyon," collector's field notes), 1 (MVZ); Trinchera, 6 (5 DMNH, 1 AMNH); Trinidad, 5 (BSC); 20 mi. E Walsenburg, "Huerfano Co." [probably Las Animas County], 1 (DMNH). Otero County: 3 mi. NW Higbee, 4300 ft., 4 (KU). Prowers County: Two Buttes peak, 4600 & 4650 ft., 2 (KU).

#New Mexico.# Union County: Clayton, 9 (BSC); 9 mi. NE Des Moines on the "Carramba River" [= Cimarron River], 1 (DMNH); Folsom, 6 (BSC); Raton Range (Oak Cañon), 8 (BSC); Sierra Grande, 9 (BSC).

#Oklahoma.# Cimarron County: Tesequite Canyon, 1 (MZ).

Museum of Natural History, University of Kansas, Lawrence. Transmitted April 20, 1953.

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