M. f. neomexicana has a large geographic range. The old male from Liberal, Seward County, Kansas, extends the known range far to the northeast. Geographically, this occurrence is logical for the southwestern desertlike conditions extend to this part of Kansas. Probably the subspecies occurs in southeastern Colorado and in the panhandle of Oklahoma where conditions are similar. Bailey (1905:198) lists neomexicana as a member of the mammalian fauna of Texas. As stated by him (loc. cit.:198) this inclusion is based on geographic grounds and not on actual specimens. Strecker (1926:13) also includes neomexicana in his list of Texas mammals but writes me, under date of January 9, 1928, that "I included Mustela frenata neomexicana as a Texas mammal on the strength of its being mentioned by Bailey. . . ." On better ground, Bailey (1928:97) lists the subspecies as occurring in southeastern New Mexico at Carlsbad Cavern. However, Bailey (loc. cit.) knew of the existence of weasels just below El Paso and at Langtry, Texas. An unsexed skeleton, no. 167891, in the United States National Museum, from Lozier, Texas, is not certainly identifiable to subspecies. If, as I think, the animal is a female, its skull is intermediate between that of frenata and neomexicana although when all features are considered it is seen to be nearest the latter. The large size (basilar length of 46.5 mm.) may reflect some relationship to texensis. The field notes of the collector furnished me by Dr. H. H. T. Jackson (MS), describe the color as brownish yellow above and sulphur below. The admission of this subspecies to the list of mammals of Texas is made certain by the female (no. 1572, Texas Cooperative Research Collection) taken on July 28, 1940, 1-1/2 mi. NW Kent, Texas, by C. E. Scull.
The skull alone from Durango (City of), extends the known range far to the south. This skull is typical of neomexicana. Skins from the same place would be especially interesting as showing the approach, if any, in color, of neomexicana to M. f. leucoparia.
Mr. D. D. Stone of Casa Grande, Arizona, writes, under date of February 2, 1927, that a weasel was seen by an acquaintance of his in a field near Chandler, Maricopa County, Arizona. Probably this was neomexicana. If so, its range extends much farther west than collected specimens show.
Actual intergradation with M. f. frenata is not shown by the material at hand. The two females from Albuquerque, although typically neomexicana as regards color, have smaller, less prominently ridged skulls than females of neomexicana of the same age from farther south and approach M. f. nevadensis.
Probably the geographic ranges of M. f. neomexicana and M. f. latirostra do not meet; the only evidence of the existence of weasels in all of the large area, comprising western Arizona and the deserts of eastern California, which intervenes between the ranges of the two subspecies is the skull of a young individual, no. 68842, Mus. Vert. Zoöl., from 10 miles northeast of Bard, Imperial County, California. There, on December 29, 1932, Jack C. vonBloeker, Jr., retrieved the weathered skull with some of the vertebrae attached, from the top of a wood rat's nest beneath a mesquite tree near the west bank of the Colorado River.
The idea that the carcass may have been washed down the river from far upstream gains no support from a comparison of the specimen itself for the tympanic bullae are larger than in nevadensis and the skull is larger than the largest males seen of arizonensis, the two upriver races. On the basis of size the skull could be either a male of latirostra or a female of neomexicana. These two subspecies, like arizonensis and the skull in question, have much inflated bullae. However, the immaturity of the specimen conceals any other diagnostic cranial features, and prevents referring it certainly to either neomexicana or latirostra. In any event the specimen provides no evidence of intergradation between the two forms last mentioned. Speculating on its identity, I should say that it might be either an intergrade between arizonensis and nevadensis, from southern Utah or northwestern Arizona, or a member of an unnamed race resident in the lower part of the valley of the Colorado River.
Whereas M. f. panamensis and M. f. aureoventris are the darkest-colored weasels and occur in regions of heavy rainfall, M. f. neomexicana is the lightest-colored American weasel and occurs in an extremely arid region where the rainfall and humidity are slight.
According to Barber and Cockerell (1898:189) "The type specimen was shot in the grass on the shore of Armstrong's Lake. . . ." Bailey (1928:97) found the tracks of one of these animals "in the great pit at the west entrance to" Carlsbad Cavern and supposes they "hunt the cave walls for mice and other small game." Data on the label attached to no. 230973 states that the specimen was taken, two miles west of Willcox, Arizona, in a prairie dog town.
Only two of the 23 skulls show evidence of infestation of the frontal sinuses by parasites.