_Plectrohyla matudai matudai_ and _P. guatemalensis_ are sympatric with _Ptychohyla schmidtorum chamulae_. Each of the first two has a bony prepollex, rugose skin on the dorsum, and heavy body. Also living with _Ptychohyla chamulae_ are _Hyla chaneque_, a large species having a tuberculate dorsum and webbed fingers, and _Hyla bivocata_, a small yellow species having a broad, flat head, small indistinct tympanum, and an axillary membrane. _Life History._--Calling males were found on leaves of herbs and bushes by cascading streams in cloud forest. The call consists of series of short notes, three to nine notes per series, sounding like "raa-raa-raa." The duration of each note is .054 to .070 of a second, and has a rate of 96 to 110 pulses per second. The dominant frequency falls between 3350 and 3450 cycles per second (Pl. 11D). The call is almost indistinguishable from that of _Ptychohyla schmidtorum schmidtorum_. Tadpoles were found in the cascading streams; the smallest tadpole has a total length of 17.2 mm. and has only 3/2 tooth-rows. At a stream 6.2 kilometers south of Rayon Mescalapa, Chiapas, metamorphosing young were found on June 16 and August 5, 1960. Each of two completely metamorphosed young has a snout-vent length of 15.7 mm. Another having a snout-vent length of 16.2 mm. has a tail stub 2 mm. long and a completely metamorphosed mouth. Two others have snout-vent lengths of 13.6 and 14.1 mm. and tail lengths of 11.5 and 8.1 mm. respectively; in these the mouth parts are incompletely metamorphosed. _Remarks._--Duellman (1961:354) described _Ptychohyla chamulae_ and stated that it probably was most closely related to _P. schmidtorum_. Further study has revealed additional resemblance in morphological and behavioral details. It is concluded that the two populations are more realistically treated as subspecies than as species. The geographic ranges, as now known, are disjunct. _Ptychohyla schmidtorum chamulae_ inhabits cloud forest on the Atlantic slopes of the Chiapan Highlands, whereas _P. s. schmidtorum_ lives in cloud forest on the Pacific slopes of the Sierra Madre in Chiapas and Guatemala. Between their known geographic ranges are the pine clad Sierra Madre and Chiapan Highlands, and intervening sub-humid Grijalva Valley. _Distribution._--This species is known only from elevations between 1500 and 1700 meters on the Atlantic slopes of the Chiapan Highlands; it is to be expected in cloud forests on the northern slopes of the Sierra de Cuchumatanes in Guatemala. _Specimens examined._--MEXICO: _Chiapas: 15 km. N of Pueblo Nuevo Solistahuacan_, UMMZ 123325 (4); _16.5 km. N of Pueblo Nuevo Solistahuacan_, UMMZ 123322 (10); _18 km. N of Pueblo Nuevo Solistahuacan_, UMMZ 121395-9, 123324 (8), 123326 (5); _18.6 km. N of Pueblo Nuevo Solistahuacan_, UMMZ 123323 (4); _5.6 km. S of Rayon Mescalapa_, KU 58062, 58200 (tadpoles); _6.2 km. S of Rayon Mescalapa_, KU 58063-74, 58199 (tadpole), 58234-8, 59936 (skeleton).