I have profited from discussions concerning this problem with several persons, most notably William E. Duellman, Hobart M. Smith, Edward H. Taylor and Charles F. Walker. Nevertheless, the ideas and conclusions presented here should not be construed as necessarily reflecting their opinions. David M. Dennis executed all of the figures, and my wife, Marsha, typed the manuscript. _Materials and Methods._--In the course of this study, 1003 specimens of the genus were examined. The holotypes of 21 of the 23 nominal species are extant; I have examined 19 of these. Nine measurements were taken, and five ratios computed for each of 338 specimens. Females are available for all species but one; thus, measurements were taken on individuals of both sexes. ANALYSIS OF CHARACTERS _Size and proportions._--Frogs of this genus range in size from 16 to 40 mm. in snout-vent length. Five species are relatively small: _S. cystignathoides_, _modestus_, _nivocolimae_, _pallidus_ and _rubrimaculatus_; one, _S. longipes_, is relatively large, and the remaining eight species are intermediate in size (22-30 mm.). Males are generally smaller than females and have proportionately longer heads and usually larger tympani. No significant differences were found among proportions, except that _S. longipes_ has a larger tympanum/eye ratio than any other species. Frogs in the _Syrrhophus marnockii_ group tend to have shorter shanks and feet, thereby giving those species a more stocky appearance. However, the differences are not significant. A summary of the data on size and proportions for the frogs of the genus _Syrrhophus_ is given in Tables 4, 5, and 6. _Hands and Feet._--Taylor and Smith (1945), Smith and Taylor (1948), Firschein (1954) and Duellman (1958) discussed the value of the palmar tubercles in identifying frogs of this genus. The eastern complex in general has a well-developed outer palmar tubercle (Fig. 1) in distinction to the western complex in which the outer palmar tubercle is reduced or absent (Fig. 2). Dixon and Webb (1966) imply that the outer palmar tubercle is rarely absent but is usually smaller than the first supernumerary tubercle of the fourth finger. My study of the western species demonstrates that the outer palmar tubercle is indeed usually present and smaller than the first supernumerary tubercle.