Part 2

Of the seven other Mexican Geophis having 15 rows of scales, four species (cancellatus, dugesii, chalybeus, and semidoliatus) have alternating pale and dark transverse markings and therefore superficially resemble aquilonaris. Of the latter two species, the poorly known G. chalybeus (Veracruz) has a much lower (137 to 142) number of ventrals than aquilonaris, and G. semidoliatus (southeastern Mexico--Veracruz, Hidalgo, and Oaxaca) has a narrower head, fewer supralabials (four to five with only the third entering the orbit), and fewer ventrals (136 to 169) than aquilonaris. Geophis aquilonaris seems to be most closely allied to G. cancellatus (Chicharras, Chiapas) and G. dugesii (known from two localities in northern Michoacán); all three species resemble one another in the number and arrangement of the scales of the head, in general coloration, and in having relatively high numbers of ventral scales (171 in cancellatus, 150 to 164 in dugesii). G. cancellatus differs from the other two species in lacking internasal scales. Geophis aquilonaris differs from both species in having a higher number of ventral and subcaudal scales, a longer tail (tail contained in snout-vent length three to four times in aquilonaris, four and one half to six times in dugesii, 11 to 12 times in cancellatus), and in having more bands on the body (28 to 32 in cancel latus, two to seven in dugesii). The belly in dugesii and cancellatus is pale but in aquilonaris it is ringed or of a solid dark color.

As more specimens of Geophis become available from intermediate localities in Mexico, it will perhaps be demonstrated that many of the kinds now thought of as full species (including those discussed above) are subspecies of a few wide-ranging species.

Remarks.--The type locality of G. aquilonaris is the small village of Barranca at the bottom of the valley of the Río Urique, several miles south and west of the continental divide. The Urique Valley, known as the Barranca del Cobre in the region south of Creel, is a deep canyon, the walls of which slope abruptly from approximately 7300 to 3000 feet and are dissected by deep side-canyons. Coniferous forest on the upper rim of the canyon is replaced by scrub vegetation on the rocky walls and by an arid tropical flora on the bottom.

Maguarachic (elevation approximately 5400 feet, longitude and latitude respectively, 108 degrees, 03 minutes W and 27 degrees, 50 minutes N) and Mojarachic (elevation approximately 7000 feet, longitude and latitude respectively, 108 degrees W and 27 degrees, 52 minutes N) are situated approximately three miles from each other and approximately 27 miles northwest of Creel. Maguarachic is given as "Mafuarachic" on the American Geographical Society map (NG 12, Baja California-Mexico, Prov. Ed., 1924). Mojarachic is not on any map of Chihuahua that I have examined.

The type and topotypic paratype were given to a member of the K.U. field party by a Mexican youth who had obtained them the previous night on the lower rocky slopes of the canyon. Both specimens were damaged by the collector piercing their heads with thorns, presumably to kill them. The type contained three oviducal eggs, each about four millimeters long. The stomachs of both specimens from Creel contained earthworms.

The presence of Geophis in this area suggests that the distribution of the genus is more or less continuous, on the western slope of the Sierra Madre Occidental, from Jalisco to southern Sonora.

I am grateful to Mr. Sydney Anderson and Mr. Ronald Pine for permission to use their field notes, to Dr. Hobart M. Smith for his examination of the specimens from Creel, to Mrs. Lorna Cordonnier for the drawings of the type, to Dr. Norman Hartweg for permitting me to study materials in his care and upon which he was making an independent study, and to Mr. Thomas M. Uzzell for locality data pertaining to the UMMZ paratypes.

Transmitted November 10, 1958.