webbed; tips of two outer fingers truncate, having terminal transverse grooves, about twice width of narrowest part of digit; digits of first and second fingers slightly expanded; fingers from shortest to longest, 1-2-4-3, first only slightly shorter than second; three palmar tubercles; inner palmar tubercle about one third size of large median tubercle; outer tubercle about one tenth size of large median tubercle; four supernumerary palmar tubercles; tips of toes slightly wider than narrowest part of digits; toes from shortest to longest, 1-2-5-3-4, second only slightly shorter than fifth; inner metatarsal tubercle about four times size of small outer metatarsal tubercle; supernumerary tubercles on foot small; no tarsal fold; heels touching when tibiae adpressed to thighs; tibiotarsal articulation reaching eye when leg adpressed to side of body.

Contrasting marbled pattern on back and top of head; contrasting, mostly barred, pattern on limbs; ventral surfaces whitish, lacking dark marks, but having minute dark peppering; marbling of dorsal surfaces blackish and whitish in preservative.

Vomerine teeth lacking; internal choanae lateral, partly concealed by maxillaries; tongue smooth, elongate, shallowly notched distally, free for about half its length; vocal sac median; internal vocal slits large and near angle of jaw.

Variation.—Twelve males closely resemble the holotype. Two specimens from Pueblo Nuevo are soft and not well preserved. The ranges of variation (means in parentheses) for the 13 males comprising the type series are: snout-vent length, 25.5-31.5 (27.9); width of head, 9.7-11.2 (10.5); diameter of eye, 2.9-3.6 (3.2); horizontal diameter of tympanum, 1.1-1.8 (1.4); length of tibia, 11.1-13.1 (12.1); length of foot, 11.0-13.1 (12.1).

The pale ground color of the marbled pattern in most specimens is least extensive on the back and arms, but most extensive on the legs. The lumbar glands are slightly elevated and conspicuous, and in KU 63328 are extremely protuberant, or (KU 63330) evident on left side but flattened and indistinct on right side. The back is rough having low, scarcely elevated pustules, but becomes less rough anteriorly and most of the top of head is smooth. The three specimens from Pueblo Nuevo, Durango, differ slightly from the other specimens examined in lacking pairs of postanal white spots, and in having smooth backs (slightly pustulate in MSU 4088). The tibiotarsal articulation fails to reach the eye in KU 63330. The small inner palmar tubercle is continuous with the large median tubercle on the right hand of KU 63330, and lacking on both hands of KU 63329 and on the left hand of KU 63328. The tip of the tongue is entire in some specimens and in others has an irregular margin.

Coloration of living specimens.—Marbled pattern on back and top of head of dark brown to blackish on yellowish-gold; pattern slightly less contrasting on limbs than on back, consisting of brown to grayish on pale yellow; side of head and body grayish sometimes having pale yellow to whitish spots; iris blackish having fine reticulation of yellowish to greenish-gold; venter dirty white.

Habitat.—The three records of occurrence for Tomodactylus saxatilis are in a mixed boreal-tropical habitat, which is transitional between a pine-oak forest at higher elevations and a tropical deciduous forest at lower elevations. The mixed boreal-tropical habitat is most conspicuous at elevations between approximately 7800 and 5500 feet on southerly exposed slopes of barrancas and arroyos of the dissected plateau of the Sierra Madre Occidental. The mixed boreal-tropical habitat occurs for approximately 30 miles along the paved highway (Mexican Highway 40) between Cd. Durango, Durango, and Mazatlán, Sinaloa. The records of occurrence in those states that are along this highway are separated by 14.5 miles (via road).