_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). [Illustration: FIG. 1. _Tomodactylus saxatilis_ new species, adult male, KU 63326, holotype (× 2), dorsal view.]