end of the drought, fishes in group (3) probably were extirpated
or decimated in other tributaries of the Wakarusa. After normal flow
recommenced in 1956, fishes re-entered the previously uninhabitable
streams or stream-segments. The rate of redispersal by various species
probably depended upon their innate mobility, and upon their tolerance
of the muddy mainstream of the Wakarusa.

Our observations suggest that certain species in group (3) dispersed
rapidly from refugia in Rock Creek, Washington Creek, and possibly Deer
Creek. These species may, of course, have survived in a few remaining
pools in tributaries throughout the basin, thereby necessitating only
minor redispersal within these tributaries following drought.

Species of group (3) that were most tolerant of drought or that
dispersed most rapidly are _Catostomus commersonnii_, _Notropis
umbratilis_, _Pimephales notatus_, and _Percina caprodes_; these were
present in the uppermost portions of the basin in 1959. Fishes having
lesser capacity for survival or dispersal are _Semotilus
atromaculatus_, _Notropis topeka_, _Phenacobius mirabilis_ and
_Campostoma anomalum_; in 1959, they were not found farther upstream
than Burys Creek. _Etheostoma spectabile_, the orangethroat darter, was
taken in Rock Creek, Washington Creek, Deer Creek, Strowbridge Creek,
Elk Creek, and at station 24 on the Wakarusa. This is a
riffle-dwelling, comparatively sedentary fish, not a strong swimmer.
These traits, coupled with the long, muddy pools and infrequent riffles
of the Wakarusa mainstream, provide a reasonable explanation of the
comparatively slow rate of dispersal by the orangethroat darter.

Several species showed no tendency for redispersal following drought,
in that they were confined to Washington Creek or Rock Creek in 1959.
_Noturus exilis_ was taken only in Washington Creek immediately below
Lone Star Lake. Rock Creek is the last stream in the Wakarusa Basin in
which _Notropis cornutus_, _Hybopsis biguttata_ and _Etheostoma nigrum_
have survived. These species require comparatively permanent streams
having pool-and-riffle habitats and gravelly bottoms for spawning.
_Hybopsis biguttata_ has been recorded only from Rock Creek, where it
was last taken in 1924. It is interesting to note that this species had
not reinvaded Smiths Branch, in Illinois, three years after the
resumption of stream-flow (Larimore _et al._, 1959). _Notropis
cornutus_ and _Etheostoma nigrum_, although