Tadpoles are definitely known of only _H. m. microcephala_ and _phlebodes_; these have been described in the preceding accounts of the species. The tadpoles of these two species can be distinguished readily (Pl. 15). The tadpole of _H. microcephala_ has a uniformly white venter and nearly transparent tail, whereas in _H. phlebodes_ the venter is flecked anteriorly and the tail is mottled. In life, _H. microcephala_ is easily recognized by the orange posterior half of the tail, whereas the tail in _H. phlebodes_ is mottled tan and grayish brown. PHYLOGENETIC RELATIONSHIPS The evidence already presented on osteology, external structure, coloration, mating call, and life history emphatically show that the four species under consideration are a closely related assemblage. Now the question arises: To what other groups in the genus is the _Hyla microcephala_ group related? Furthermore, it is pertinent to this discussion to attempt a reconstruction of the phylogeny of the group as a whole and of the individual species in the _Hyla microcephala_ group. With regard to the relationships of the group we must take into account certain species in South America. Our endeavors there are hampered by the absence of data on the mating calls and life histories of most of the relevant species. As mentioned in the account of _Hyla m. microcephala_, the species _microcephala_ possibly is subspecifically related to _Hyla misera_, a frog widespread in the Amazon Basin. _Hyla misera_ resembles _microcephala_ in coloration, external structure, and cranial characters. The frontoparietals are equally poorly ossified, and the frontoparietal fontanelle is extensive. Our principal reason for not considering the two taxa conspecific at this time is our lack of knowledge concerning the color of living _H. misera_, the structure of the tadpoles, and the characteristics of the mating call. Even with the absence of such data that we think essential to establish the nomenclature status of the taxa, we are confident that the two are sufficiently closely related that any discussion of the phylogenetic relationships of one species certainly must involve consideration of the other.