|ANIMALS THAT LIVE IN CAVES.|
THE study of paleontology and prehistoric archæology and the exhumation of the life of the past in caverns have been pursued in France during the last twenty years at the expense of the investigation of the present life, while the fauna and flora of their black recesses and dark waters have nevertheless flourished quite as vigorously as in the subsoils of Austria and America. The naturalists of those countries have, however, carried their investigations in that domain considerably further than those of France, Still, numerous cave-dwelling species new to us have been found in the Pyrenees and the south and east of France.
The zoölogical study of subterranean waters is eminently useful to hygienists, to whom it discloses the presence of noxious organisms capable of developing in the water supplies of cities, and thence finding their way into the human economy.
Animals of all classes may be found in caverns. Some, which do not pass all their existence there, but seek shelter in them, have been called by the Austrian Schiner troglophiles (or cave lovers), and others, which never leave their dark abodes, are designated by him as troglobiens (or cave dwellers). I can not present here even a simple picture of the subterranean fauna actually known; I can hardly even sketch the outlines of the subject and insist on its importance.
The higher vertebrates—mammals, birds, and reptiles—found in caves seem to be chiefly troglophiles. There are, however, real troglobiens among the lower vertebrates—batrachians and fishes. The articulates, in particular, and especially the arthropods—insects, myriapods, arachnids, and crustaceans have revealed many species previously unknown. The Dolichopoda palpata, represented in the figure, was discovered by M. E. Simon, in 1879, in the grottoes of Belves and Espezel, in the Aube. Worms, mollusks, etc., are not rare.
The list of the fauna of the Mammoth Cave in Kentucky comprises no less than a hundred species, without counting those that come in casually from without. Blind spiders set their nets for eyeless flies. Fish eat crawfish, which feed upon smaller crustaceans pulled with their pincers from beneath the flat rocks, while the crustaceans prey upon defenseless mollusks, and these forage upon microscopic fungi.
The important question of the origin of the subterranean fauna is still invested with a degree of mystery. It was at one time believed and maintained by Agassiz that they were specially created for the medium in which they live. It was afterward recognized