48 
Carter R. Gilbert 
would have been in the area around Moultrie, Georgia, where these two 
drainages come in close proximity (Fig. 1). 
Reference was made earlier to the caves and springs that are so 
prevalent throughout the northern half of peninsular Florida (Rosenau 
et al. 1977). These result from the highly soluble limestone substrate 
that underlies the region, and they support a distinctive and highly 
endemic invertebrate fauna, particularly the crayfishes (Franz and Lee 
1982). Many vertebrate animals inhabit the springs and spring runs, 
although only a few move very far into the underground aquifer (Relyea 
and Sutton 1973). One of these, the cyprinid fish Notropis harperi, 
probably is more closely associated with a spring habitat than any other 
fish in eastern North America (Gilbert 1980c), and in fact this extremely 
close ecological association was an important consideration in hypothe- 
sizing a north Florida-south Georgia origin for the species. Despite this, 
no troglobitic fish is known from either this area or the independent 
Marianna cave system in southeastern Alabama, southwestern Georgia 
and closely adjacent areas in Florida. No other troglobitic vertebrates 
are known from the north Florida-south Georgia area, although a 
cavernicolous salamander, Haideotriton wallacei , is known from caves 
in the Marianna area and from one cave in the adjacent Dougherty 
Plain of southwestern Georgia. 
Notropis harperi and Ictalurus natalis move considerable distances 
underground, and are the only fish species in the north Florida area that 
have naturally reached isolated sink holes and springs in this way 
(Hubbs and Crowe 1956, Relyea and Sutton 1973). Hubbs and Crowe 
(1956) described the isolated sinkhole populations of N. harperi as a 
new subspecies, N. h. subterranea, but Howell (1960) showed this not to 
be valid. 
This brings us to the question of why troglobitic fishes apparently 
have not evolved in the Florida caves, especially considering that obli- 
gate cavernicoles are numerous among the crustaceans and other inver- 
tebrates of peninsular Florida. This situation becomes even more enig- 
matic in view of the presence of Chologaster cornuta , a species of the 
cavefish family Amblyopsidae, on the Atlantic slope as far south as cen- 
tral Georgia (Cooper and Rohde 1980). A congener, Chologaster agas- 
sizi, inhabits springs and caves of the central Mississippi valley (Cooper 
1980). Chologaster cornuta occurs in quiet, dark, well-protected situa- 
tions that in some respects resemble the cave environment (Poulson 
1963). Based on habitat preferences and present geographic distribu- 
tions, it is virtually certain that this amblyopsid group reached the 
Atlantic slope via movement along the coastal plain, presumably prior* 
to the Pliocene, and thus should have had access to Florida caves. It is 
