The terrain consists of occasional level areas, but is mostly of steep hillsides. Dominant trees are large oaks and pines; a characteristic pine is the sad or drooping-needle pine, locally called "pino triste." The vegetational cover is usually open, including grasses, small oaks and pines, broad-leaved shrubs and herbs, prickly pears, magueys, thorny acacias, bracken fern, and epiphytes in trees. Ferns occur in moist protected places, and orchids are occasional, sometimes in trees. Outcrops of rock, boulder-strewn areas, and occasional rock slides (talus) also characterize the terrain. _Tomodactylus saxatilis _seems to be restricted to rocky habitats. The individuals collected were detected when they called at night from within crevices of rocks or from exposed perches on rocks and boulders; some calling frogs were out of reach on steep rock walls. The call is a single, loud, high peep. _Comparisons._--Dixon (1957) recognized six species of _Tomodactylus_ (_nitidus_, _dilatus_, _albolabris_, _angustidigitorum_, _fuscus_ and _grandis_) in his revision of the genus. Another species (_rufescens_) was subsequently described by Duellman and Dixon (1959). _Tomodactylus saxatilis_ differs from all the species named immediately above by the combination of characters given in the diagnosis. _Tomodactylus saxatilis_ differs from _nitidus_, _angustidigitorum_ and _grandis_ in having the tips of the two outer fingers widened and truncate; _saxatilis_ differs from _dilatus_, _albolabris_, _fuscus_ and _rufescens_ in having a smooth venter (not pustulate), a contrasting pale and dark marbled pattern on the back, and a lack of "flash" colors on the femora.