THE MAMMOTH CAVE AND ITS INHABITANTS. 755 
able vigorously to discriminate between the two. We shall ac- 
cordingly look upon the subterranean fauna, or more properly 
faunas, as small ramifications which have penetrated into the earth 
from the geographically-limited faunas of the adjacent regions ; 
and which, as they extended themselves into darkness, have been 
accommodated to surrounding circumstances. Animals not far re- 
mote from the ordinary forms, prepare the transition from light to 
darkness. Next follow those that are constructed for taiigats 
and on of all those destined for total darkness, and whose struc- 
s quite peculiar. Among these some are adapted for pooli 
localities, those which inhabit dry localities or detached little 
reservoirs being totally blind, while others, destined for running 
streams, have eyes of imperfect ee so as to receive the 
impression of rays of light, but no proper image o of illuminated 
objects. e may therefore with tolerable ion arrange the 
inhabitants of caverns under the following heads :— 
Shade animals. — Extensive genera and species inhabiting cav- 
erns near their entr cies and, generally, all cool, shady and moist 
localities. Of these, those that fly occasionally. enter far into the 
caverns (Diptera). 
Twilight animals.—They belong to widely spread genera, but 
are peculiar to the caves, and distinguished by their small eyes. 
hey are principally found near the entrances to the caves, oe 
although wingless, they penetrate often the whole extent of the 
dark space. — ( Pristonychus elegans, Homalota spelea.) 
Cave animals. — They form, a least in part, peculiar genera, are 
wingless and colorless, as far as the consistency of their integu- 
ments will admit, and exist exauaacnety in total darkness. The 
terrestrial division is blind ; the aquatic has a perception of light. 
group belong all the animals in the Mammoth Cave, and 
among those of the caves of Carniola, Anophthalmus, Bathyscia, 
perhaps likewise Anurophorus a Hypochthon, which, however, 
may belong to the following gro 
Stalactite cave animals. ar OEP Arachnidans and Crustaceans 
Etnis to peculiar genera, wingless, blind, brightly colored 
ccording to the nature of their integuments, either “light brown, 
yellowisn white, or snow white, perhaps a according to the pre- 
ponderance of the chitine ; living in total darkness, ares to 
stalactite caves, in part occupying the columns and constru ructed 
accordingly, either for ascent or hovering over them. Here belong 
most of the animals treated of in this memoir Stagobius, Blo- 
thrus, Stalita, Niphargus, and Titanethes 
A pertinent question arises as to the hee of the formation of 
these caves and when they became inhabitable. As previously stat- 
matin all deta Repos [ie Salma), or viie aot eos 
he discriminates six s 
AMER. Saroka, VOL. V 48 
