Dried skins of all species of _Smilisca_ were sent to Jose M. Cei, Instituto Nacional de Cuyo, Mendoza, Argentina, for biochemical screening by means of the chromatographic techniques described by Erspamer and Cei (1963). The species in the _baudini_ group have detectable amounts of penta-hydroxi-trypatamine, whereas only a trace is present in the other species. Furthermore, species in the _baudini_ group differ from _S. sila_ and the _sordida_ group in lacking, or having only a trace of, tryptophan-containing polypeptides. These superficial biochemical tests support the arrangement of species as ascertained by conventional taxonomic characters. External Morphological Characters The features of external morphology that were studied in connection with the taxonomy of the genus _Smilisca_ are discussed below. _Size and Proportions_ The frogs of the genus _Smilisca___ are medium to large tree frogs. The three species comprising the _baudini_ group (_S. baudini_, _cyanosticta_, and _phaeota_) are notably larger than _S. puma_, _sila_, and _sordida_ (Table 6). The largest specimen that we examined is a female of _S. baudini_ having a snout-vent length of 90 mm. _Smilisca puma_ is the smallest species; the largest male has a snout-vent length of 38 mm. and the largest female, 46 mm. Table 6.--Comparison of Sizes and Certain Proportions of the Species of Smilisca. (Means in Parentheses Below Observed Ranges; Data for Males Only.) ================+====+===========+=============+===========+ | | Snout-vent|Tibia length/| Tympanum/ | Species | N | length | snout-vent | eye | ----------------+----+-----------+-------------+-----------+ | | | | | _S. baudini_ |140 | 47.3-75.9 | 42.1-53.6 | 56.1-94.4 | | | (58.7) | (47.8) | (73.5) | | | | | | _S. cyanosticta_| 40 | 44.6-56.8 | 51.9-59.7 | 62.7-88.4 | | | (50.7) | (56.0) | (71.4) | | | | | | _S. phaeota_ | 50 | 40.8-65.5 | 50.9-60.2 | 62.7-85.5 | | | (53.9) | (55.5) | (76.6) | | | | | | _S. puma_ | 20 | 31.9-38.1 | 48.2-53.1 | 52.1-72.2 | | | (34.7) | (51.3) | (64.9) | | | | | | _S. sila_ | 33 | 31.6-44.8 | 49.7-58.1 | 47.6-58.3 | | | (37.7) | (54.8) | (53.2) | | | | | | _S. sordida_ | 55 | 31.9-44.6 | 50.5-57.1 | 46.5-57.1 | | | (37.9) | (53.4) | (49.1) | ----------------+----+-----------+-------------+-----------+