249 
son Science Fund and through the courtesy of the officers of the Monon, 
the L. E. and St. L. and the Frisco R. R. lines, I was enabled to visit 
the cave region of Missouri again. This time I visited nine caves and 
secured eight specimens. I have since received an additional number 
from a correspondent. From information gathered it would seem that 
this species (or similar ones) has a wide distribution in the subterranean 
water of the southern half of Missouri and northern Arkansas, probably 
also the eastern part of Kansas. 
. 
On the surface the specimens very cosely resemble Typhlichthys sub- 
terraneus from Mammoth Cave, ditrering slightly in the proportion and in 
the pectoral and caudal fins. These fins are longer in rose. It is, how- 
ever, quite evident from a study of their eyes that we have to deal here 
with a case of convergence of two very distinct forms. They have con- 
verged because of the similarity of their environment and especially owing 
to the absence of those elements in their environment that lead to external 
protective adaptations. The details of the structure of the eyes of all the 
members of the Amblyopsidz will be published shortly, and I need call 
attention here only to the structures that warrant the conclusion that the 
cis and transmississippi forms of blind fishes without ventral fins are of 
distinct origin. The blind fish Amblyopsis may be left out of considera- 
tion, since it is the only member of the family that possesses ventral fins. 
Otherwise, it would be difficult to distinguish specimens of similar size of 
this species from either subterraneus or rose. 
