_Specimens examined._--(62). MEXICO, _Guerrero_: Acapulco, UMMZ 110125; 6.4 km. N Acapulco, FMNH 100389, 100525; Agua del Obispo, 980-1000 m., FMNH 75791, 100518-21, 100526, KU 86884-86, UIMNH 13315, UMMZ 119152, 125890 (4); 13.3 km. NW Coyuca, UIMNH 38367, 71982-83; 14.5 km. S Mazatlan, FMNH 100072 (holotype), 100408, 100511-17, UIMNH 13302-309; Tierra Colorado, 300 m., KU 67961, UIMNH 13313-14; near El Treinte, FMNH 126639; Xaltinanguis, FMNH 100522-24, 126640. _Oaxaca_: Cacahuatepec, UIMNH 52853; 8 km. NW Rio Canoa, 53 km. ESE Cuajinicuilapa, UIMNH 52852; 6.4 km. N El Candelaria, UIMNH 9501; 11.2 km. S El Candelaria, UIMNH 9502; 17 km. NE Juchatengo, 1600 m., KU 86887; 31.5 km. N Pochutla, UMMZ 123999 (2); 32.9 km. N Pochutla, 850 m., UMMZ 123996; 37.1 km. N Pochutla, UMMZ 123998 (2); 41.4 km. N Pochutla, UMMZ 123997 (2); Cerro Quiengola, FMNH 105653; 3.8 km. N Santiago Chivela, UMMZ 115449; 14.5 km. W Tehuantepec, UMMZ 115448 (2). =Syrrhophus interorbitalis= Langebartel and Shannon _Syrrhophus interorbitalis_ Langebartel and Shannon, 1956: 161-65, figs. 1-2 [Holotype.--UIMNH 67061 (formerly FAS 9378), 36 mi. N Mazatlan, Sinaloa, Mexico, collected on November 17, 1955, by E. C. Bay, J. C. Schaffner, and D. A. Langebartel]. Duellman, 1958:1-4, 10, 12, 14. Gorham, 1966:164-65. _Syrrhophis interorbitalis_: Campbell and Simmons, 1962:194, fig. 1. [Illustration: FIG. 18: Left to right. _Syrrhophus interorbitalis_ (UIMNH 38095, x1.5), _S. nivocolimae_ (LACM 3203, x1.3), and _S. teretistes_ (KU 75263, x1.5).] _Diagnosis._--Medium sized frogs, only known male 25.6 mm. snout-vent, females 20.0-26.7 mm. snout-vent length (small sample); vocal slits in males; finger tips expanded; first finger shorter than second; outer metatarsal tubercle one-third size of inner; skin of dorsum shagreened, that of venter smooth; diameter of tympanum 37.7-42.4 per cent that of eye in both sexes; pale yellow-brown ground color mottled with brown; limb bands broad, much wider than narrow light interspaces; interorbital bar very long, edged with dark brown to black (Fig. 18). _Remarks._--Duellman's (1958) measurements and proportions of _S. interorbitalis_ were based exclusively on the type series, which is composed of only females; therefore his _interorbitalis_ data are not comparable with the data for the other species in his table. Campbell and Simmons (1962) collected the only known male. The type series was collected beneath rocks in a stream bed; the collectors heard calling frogs in the bushes but were unable to obtain specimens (Langebartel and Shannon, 1956). Campbell and Simmons (1962) reported that their specimen had a poorly developed interorbital bar in life; in preservative the bar compares favorably with the bar in the female (Fig. 18). _Etymology._--Latin, in reference to the pale interocular band. _Distribution._--Pacific lowlands of Sinaloa, Mexico (Fig. 20).