No outstanding differences in proportions exist between species, although certain proportions are sufficiently different in some species to warrant mention. _Smilisca baudini_ is a more squat and stocky frog than other members of the genus; this is reflected in the somewhat shorter hind legs (Table 6). The size of the tympanum relative to that of the eye is highly variable within samples of a given species. Even so, noticeable differences in the tympanum/eye ratio are apparent. Members of the _baudini_ group have the largest tympani, whereas _S. sila_ and _sordida_ have the smallest, and _S. puma_ is intermediate (Table 6). _Shape of Snout_ Although all members of the genus have rather truncate snouts, subtle differences exist among the species (Pl. 12). _Smilisca sila_ has the shortest snout; that of _S. baudini_ is only slightly longer. The snouts of _S. cyanosticta_ and _puma_ are nearly square in lateral profile, whereas those of _S. phaeota_ and _sordida_ are slightly inclined. The shape of the snout is relatively uniform within each species and displays no noticeable sexual dimorphism, except in _S. sordida_, in which there are sexual differences and geographic variation (see p. 324). _Hands and Feet_ The characters of the hands and feet are among the most taxonomically important external features in _Smilisca_. Consistent differences exist in relative lengths of the digits, size of subarticular tubercles, size and number of supernumerary tubercles, size and shape of the inner metatarsal tubercle, and amount of webbing (Pls. 4 and 5). In the _baudini_ group the series of species (_baudini-phaeota-cyanosticta_) show a progressive increase in amount of webbing in the hand and a decrease in number, and corresponding increase in size, of supernumerary tubercles. The amount of webbing in the feet of _S. baudini_ and _phaeota_ is about the same, but the webbing is slightly more extensive in _S. cyanosticta_. _Smilisca puma_ is unique in the genus in lacking webbing in the hand; furthermore, this species is distinctive in having many large subarticular tubercles on the hand and a relatively small inner metatarsal tubercle. The two stream-inhabitants, _S. sila_ and _sordida_, have shorter and stouter fingers than the other species. The webbing is most extensive in both the hands and feet of these species, which also are distinctive in having many small supernumerary tubercles on the feet. _Ontogenetic Changes_