Although the type locality is stated to be Santa Efigenia on the Pacific slopes of the Sierra Madre de Chiapas in eastern Oaxaca, the type specimen probably came from the northern slopes of the mountains. All other known specimens are from the Gulf slopes and lowlands, and from several localities in Los Tuxtlas. Details concerning specimens from the isthmus and other parts of the range were given by Duellman (1958c:8). Smith (1947:408) reported a specimen of _Syrrhophus verruculatus_ Peters from San Lorenzo, Veracruz; he stated that this specimen (USNM 123530) could not be _S. leprus_, because it had a gray belly, nor _S. cystignathoides_, because of the dark and light dorsal coloration. Firschein (1954:57) in his review of the species of _Syrrhophus_ in eastern Mexico referred the specimen to _S. cystignathoides_. The specimen is in poor condition. Nevertheless, specific determination is possible. Numerous specimens of _S. leprus_ from Los Tuxtlas have gray bellies; some have heavier pigmentation than the specimen from San Lorenzo. In preservative the dorsum is dark brown with lighter mottling. There is little doubt that the specimen from San Lorenzo is a _Syrrhophus leprus_, an abundant and widespread species in the humid Gulf lowlands of southern Mexico, and not _verruculatus_, if this is a valid species (see Firschein, _op. cit._:58), and not _cystignathoides_, a species known from San Luis Potosi southward to central Veracruz. =Syrrhophus pipilans pipilans= Taylor _Oaxaca_: Cerro Arenal; Cerro San Pedro; 6 km. N of Chivela; 14 km. W of Tehuantepec (2). In the isthmian region this frog is known only from the Pacific slopes and the Plains of Tehuantepec. Males call from the ground and from trees to heights of about four meters. The call is a single, high, long "peep." =Engystomops pustulosus= Cope _Oaxaca_: Chivela; La Ventosa (3); Santo Domingo; Tapanatepec (14); Tehuantepec (61); Union Hidalgo (62). _Veracruz_: Acayucan; Cuatotolapam (7); 10 km. SE of Hueyapan (11). Large congregations were breeding at Tehuantepec on July 5, at Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs were breeding in open ponds in scrub forest and savanna; none was found in the rainforest. Males call while floating on the water (Pl. 7, fig. 1); the call is a soft "do-ing, do-ing" with a rising tone on the last note. Numerous individual egg masses were along the bank of a pond near Tehuantepec; one large composite egg mass there had a surface area of about one square meter (Pl. 7, fig. 2). The large series from Union Hidalgo was obtained by digging specimens out of a dry sandy river bank in the dry season. Some of the individuals were buried to a depth of 25 centimeters.