group were, on the average, larger than the
individuals shown in Fig. 6, and they made less rapid growth.]

The population which I studied may be considered typical of _G.
olivacea_. They averaged large, including individuals up to 42 mm. in
length, well above the maximum sizes for any reported in the literature.
At metamorphosis these _olivacea_ are of approximately 50 percent
greater length than _G. carolinensis_ as reported by Wright and Wright
(1949: 573) and Anderson (1954: 41). Yet Blair (1950: 152) observed that
in eastern Oklahoma, where the ranges of _olivacea_ and _carolinensis_
overlap, the latter is larger. On the basis of field and laboratory
observations he tentatively concluded that one of the main barriers to
interbreeding was the reluctance of the males of _carolinensis_ to clasp
the smaller females of _olivacea_.

That size differs in different populations, and is still poorly
understood, is illustrated by the following discrepant figures from
various authors.

TABLE 4. SIZE RANGE OF ADULTS IN VARIOUS POPULATIONS OF GASTROPHRYNE.

===============+=======================+=================+=============
Species or | Geographic population | Authority |Size range of
subspecies | sampled | |adults in mm.
---------------+-----------------------+-----------------+-------------
| | |
_olivacea_ |Douglas Co., Kansas |present study | 31 to 42
| | |
_olivacea_ |entire range |Wright and Wright| 19 to 38
| | (1949) |
| | |
_carolinensis_ |entire range |Wright and Wright| 20 to 36
| | (1949) |
| | |
_carolinensis_ |southern Louisiana |Anderson | 22 to 35
| | (1954) |
| | |
_areolata_ |southeastern Texas |Wright and Wright| 23 to 29
| | (1949) |
| | |
_mazatlanensis_|Arizona and New Mexico |Wright and Wright| 22 to 30
| | (1949)