CAVE FA LTN.E. The richest cave fauna) occur in southern Franco, in limestone deposits near or at the base of the Pyrenees, though the great grotto of Adelsberg, near Triest, is the classic abode of cavernitolous forms, including the Mind triton, eyeless beetles, etc. In North America Mammoth and Wyandotte caves, with many smaller ones in their vicinity, as well as the caves in Carter County, Ky., also Weyer's Cave and the Luray Caverns in Virginia, have been especially explored, and have yielded a most varied and in teresting fauna. These regions have been honey combed by the action of subterranean streams now mostly dried up. With these systems of subterranean drainage are associated sink-holes, and deep, dark wells inhabited' by blind fish, crayfish, and other ernstacea of the same spe cies as those inhabiting the caves. Other caves more or less tenanted by blind forms are situ ated in Mexico, at Cacahuamilpa, in open sink holes in Cuba, as well as in caves and wells in NOW Zealand. The caverns inhabited by per manent assemblages of blind animals both in America and Europe lie south of the ice sheet of the glacial period. The cave fauna probably
became established at the beginning of the Qua ternary epoch— i. e. very soon after the close of the Tertiary period.
Taking the Mammoth Cave as the type of a great system of underground passages and cham bers, let its consider the conditions under which these blind animals live. The total length of the avenues is about 150 miles. In the older and dry passages and chambers there is little life ; the animals are mostly congregated in the newer or comparatively damp places, the aquatic forms living in the streams and pools. There is no vegetation. except a few scattered molds and fungi. The food is scanty, and the animals arc all carnivorous, preying on (tile another. The temperature is very equable, the mean for the winter months being 53° F., and for the sum mer 5-I° F., the variation throughout the year being scarcely more than one degree.
The number of species thus far detected in Mammoth Cave is about seventy-five, and in other American eaves about forty or fifty more, while there are several hundred kinds existing in European