_Remarks._--Evidence for intergradation of _Hyla microcephala_ with _H. underwoodi_ is provided by four specimens [USC 818 (2), 6081-2] from 6.1 kilometers northeast of the mouth of the Río Tarcoles, and nine specimens [USC 8254 (2), 8255, 8256 (4), 8258 (2)] from Parrita, both in Puntarenas Province, Costa Rica. These localities lie about two-thirds the distance from the northwesternmost locality for _H. m. microcephala_ (Palmar Sur) to the southeasternmost locality for _H. m. underwoodi_ (Barranca). Although in most aspects of coloration the frogs are more nearly like _H. m. underwoodi_ than _H. m. microcephala_, some specimens have longitudinal lines on their shanks, such as are characteristic of _H. m. microcephala_. The dorsal pattern varies from nearly complete longitudinal lines to broken lines, fused into an X-shaped scapular mark or not. As noted by Rivero (1961:135), _Hyla microcephala_ seems to be closely related to _Hyla misera_ Werner, a species having a wide distribution east of the Andes in South America. Despite the similarity in color pattern, size, and structure, we are reluctant to place the two taxa in the same species until data on coloration in life, mating calls, and life history are available for _Hyla misera_ and compared with those of _Hyla microcephala_. The status of Cope's _Hyla cherrei_ is questionable. Since the type, the only specimen ever referred to the species, apparently is lost, the only extant information regarding the taxon is contained in the original description (Cope, 1894). There the species was characterized as having a narrow dorsolateral white stripe and lacking pigment on the upper arms and thighs. These characteristics of the color pattern combined with the statements "vomerine teeth few, opposite the middle of the very large choanae" and "tympanic drum distinct, one half the area of eye" serve to distinguish _H. cherrei_ from all other Costa Rican hylids, except _H. m. microcephala_ and _H. m. underwoodi_. No statements in the type description will definitely associate _cherrei_ with one or the other of these subspecies. Since it seems obvious that _H. cherrei_ can be associated with _H. microcephala_, we prefer to place the name in the synonymy of the nominate subspecies, thereby preserving the commonly used name _H. underwoodi_ (Boulenger, 1899) as a subspecies of _H. microcephala_.