In the savannas _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and _Gastrophryne usta_ are fossorial species. _Bufo marinus_, _Leptodactylus melanonotus_, _Leptodactylus labialis_, _Rana palmipes_, and _Rana pipiens_ are found in the vicinity of permanent water in the savannas. Although the savanna habitat does not provide the ecological conditions for the existence of an arboreal fauna, many arboreal species from the surrounding rainforest utilize the extensive marshes and ponds in the savannas for breeding purposes. Thus, _Hyla baudini_, _Hyla microcephala martini_, _Hyla picta_, and _Phrynohyas spilomma_ have been found breeding in savannas. In parts of savannas where clumps of trees surround depressions containing water throughout the year, individuals of the species named above, together with _Hyla loquax_ and _Phyllomedusa callidryas taylori_, may not only breed, but remain throughout the year. In the semi-arid scrub forest the same fossorial species as exist in the savannas are found. Likewise, _Bufo marinus_, _Leptodactylus labialis_, _Leptodactylus melanonotus_, and _Rana pipiens_ are found near permanent water. Terrestrial species in this semi-arid environment include _Bufo canaliferus_, _Bufo coccifer_, _Bufo marmoreus_, _Syrrhophus pipilans_, and _Diaglena reticulata_. Of these, _Syrrhophus pipilans_ sometimes inhabits low trees and bushes; the others may be fossorial. The arboreal species in the scrub forest include _Hyla baudini_, _Hyla robertmertensi_, _Hyla staufferi_, and _Phyllomedusa dacnicolor_. _Eleutherodactylus rugulosus_ and _Hylella sumichrasti_ live along streams in the scrub forest. _Hylella sumichrasti_ lays its eggs in these streams. In comparing the ecological differences in the amphibian assemblages in the three major habitats, the most obvious difference is the great percentage of arboreal species in the rainforest as compared with savanna and scrub forest. Only four arboreal species are found in the scrub forest, none in the savannas, but eleven in the rainforest. Likewise, there is an absence of ground-dwelling forms in the arid habitats; in the latter the only terrestrial species are those that are found near water. A possible exception is _Syrrhophus pipilans_. From the above analysis of ecological distribution we may see that the rainforest provides a variety of habitats for amphibians and that these habitats are suitable for amphibian life throughout the year. On the other hand, the savannas and scrub forests are characterized by extreme conditions of desiccation, a factor of considerable importance in limiting the ecological distribution of amphibians. However, there still is a diversity of amphibians in these semi-arid environments. Obviously, these species are adapted in various ways for survival during the dry season, at which time environmental conditions are such that the animals cannot carry on their normal activities.