ained by Freiburg, corroborating and extending his
conclusions in most instances, and also indicating that certain of his
tentative conclusions need to be revised.

While the present report was in preparation, Anderson (1954) published
an excellent account of the ecology of the eastern species _G.
carolinensis_ in southern Louisiana. Anderson's findings concerning this
closely related species in a much different environment have been
especially valuable as a basis for comparison. The two species are
basically similar in their habits and ecology but many minor differences
are indicated. Some of these differences result from the differing
environments where Anderson's study and my own were made and others
certainly result from innate genetic differences between the species.

The frog with which this report is concerned is the _Microhyla
carolinensis olivacea_ of the check list (Schmidt, 1953: 77) and recent
authors. De Carvalho (1954: 12) resurrected the generic name,
_Gastrophryne_, for the American species formerly included in
_Microhyla_, and presented seemingly valid morphological evidence for
this plausible generic separation.

_G. olivacea_ is obviously closely related to _G. carolinensis_; the
differences are not greater than those to be expected between well
marked subspecies. Nevertheless, in eastern Oklahoma and eastern Texas,
where the ranges meet, the two kinds have been found to maintain their
distinctness, differing in coloration, behavior, calls, and time of
breeding. Hecht and Matalas (1946: 2) found seeming intergrades from the
area of overlapping in eastern Texas, but some specimens from this same
area were typical of each form. Their study was limited to preserved
material, in which some characters probably were obscured. More field
work throughout the zone of contact is needed. The evidence of
intergradation obtained so far seems to be somewhat equivocal.

Besides _G. olivacea_ and typical _G. carolinensis_ there are several
named forms in the genus, including some of doubtful status. The name
_mazatlanensis_ has been applied to a southwestern population, which
seems to be a well marked subspecies of _olivacea_, but as yet
_mazatlanensis_ has been collected at few localities and the evidence of
intergradation is meager. The names _areolata_ and _texensis_ have been
applied to populations in Texas. Hecht and Matalas (1946: 3) consider
_areolata_ to be a synonym of _olivacea_, applied to a population