_Life History._--At Vista Hermosa, Oaxaca, males were calling on vegetation above small streams on March 30, 1959, and on June 28, 1962; males were found on vegetation overhanging a stream 6 kilometers south of Vista Hermosa on June 27 and July 3, 1962. The call consists of a series of short notes, three to thirteen notes per series, sounding like "raa-raa-raa." The duration of each note is about .08 of a second and has a rate of 123 to 129 pulses per second. The dominant frequency of notes in short series is about 2100 cycles per second, whereas the dominant frequency of notes in long series is about 3150 cycles per second (Pl. 11E). On June 28, 1962, two tadpoles of this species were found in a quiet pool in a spring-fed rivulet at Vista Hermosa, Oaxaca. Females are unknown. _Remarks._--The absence of a tarsal fold and of nuptial spines in breeding males, the nature of the breeding call, and the form of tadpole are characters that place _Ptychohyla ignicolor_ in the _P. schmidtorum_-group. _Distribution._--This species is known from only two localities at elevations of 1500 and 1850 meters in the cloud forest on the northern (Atlantic) slopes of the Sierra Madre Oriental in northern Oaxaca. _Specimens examined._--MEXICO: _Oaxaca: Vista Hermosa_, KU 71334, 71716 (tadpoles), UMMZ 119602; 6 km. S of Vista Hermosa, KU 71335-42, 71343 (skeleton), UMMZ 119603, 123327 (2). DISTRIBUTION AND ECOLOGY Geographic Distribution of the Species The distribution of species of _Ptychohyla_ reflects the distribution of cloud forest in southern Mexico and northern Central America. The frogs are restricted to mountainous areas, usually at elevations higher than 1000 meters above sea level. _Ptychohyla_ does not range to great heights in the mountains, where west of the Isthmus of Tehuantepec the mountain streams are inhabited by frogs of the _Hyla bistincta_ group, and in Chiapas and Guatemala by species of _Plectrohyla_. Frogs of the _Ptychohyla euthysanota_ group have a greater combined geographic range than the species comprising the _Ptychohyla schmidtorum_ group (Fig. 7). No two species in the same group are sympatric, but members of different groups are sympatric in at least parts of their ranges. Apparently _P. leonhardschultzei_ ranges around the southern edge of the Mexican Highlands, where the species occurs on both Atlantic and Pacific slopes; as can be seen from the distribution map, there are many gaps in the known range of this species. The range of _P. euthysanota euthysanota_ is along the Pacific slopes of the Sierra Madre in Chiapas, Guatemala, and El Salvador, whereas that of _P. euthysanota macrotympanum_ is along the southern interior slopes of the Central Highlands of Chiapas and the Sierra de Cuchumatanes in Guatemala. _Ptychohyla spinipollex_ occurs on the wet Atlantic slopes of the Guatemalan and Honduranean Highlands; the range of the species in Honduras is poorly known.