_Remarks._--The known distribution of _Plectrohyla hartwegi_ includes three localities at elevations of 1000 to 2050 meters in the Sierra Madre of Chiapas and extreme eastern Oaxaca. The specimen from Paraje El Triunfo was found in a rocky stream in cloud forest at an elevation of 2050 meters. One _Plectrohyla sagorum_ was obtained from the same stream. Eizi Matuda sent the holotype to the late Dr. Norman Hartweg, who recognized that the specimen was unique but was reluctant to name the species on the basis of a single specimen. Now that two additional specimens are available, it seems appropriate to associate Hartweg's name with this new species of _Plectrohyla_, a genus that Hartweg first adequately defined. LITERATURE CITED ADLER, K. 1965. Three new frogs of the genus _Hyla_ from the Sierra Madre del Sur of Mexico. Occas. Papers Mus. Zool. Univ. Michigan, 642:1-18, pl. 1, December 16. DUELLMAN, W. E. 1960. Synonymy, variation, and distribution of _Ptychohyla leonhardschultzei_ Ahl. Studies of American hylid frogs, IV. Herpetologica, 16:191-197, September 23. 1964. A review of the frogs of the _Hyla bistincta_ group. Univ. Kansas Publ. Mus. Nat. Hist., 15:469-491, March 2. 1965. Frogs of the _Hyla taeniopus_ group. Copeia, 2:159-168, June 25. STARRETT, P. 1966. Rediscovery of _Hyla pictipes_ Cope, with description of a new montane stream _Hyla_ from Costa Rica. Bull. South. California Acad. Sci., 65 (1):17-28, March. _Transmitted July 11, 1967._ [Illustration: PLATE 17 Upper figure, _Hyla xanthosticta_ (KU 103772); lower figure, _Hyla pseudopuma infucata_ (KU 101770). x 2.] [Illustration: PLATE 18 Upper figure, _Hyla pellita_ (KU 100973); middle figure, _Hyla pellita_ (KU 100970); lower figure, _Hyla siopela_ (KU 100977). x 2.] [Illustration: PLATE 19 Upper figure, _Hyla altipotens_ (KU 101001); lower figure, _Plectrohyla hartwegi_ (UMMZ 94428). x 1.] 31-9420 Transcriber's Notes: Obvious punctuation errors corrected. Spelling corrections: 'Mexico' to 'Mexico' on title page for consistency. 'granulelike' to 'granule-like' ...large, granule-like, present... 'midlevel' to 'mid-level' ... at mid-level of thighs... 'posterio' to 'posterior' ...anterior and posterior surfaces of thighs... 'flank' to 'flanks' ...mottling on flanks...