The discovery of animals adapted for perpetual darkness is but of modern date, and as the vast majority of caves have not yet been thoroughly explored by zoologists, the number of genera and species already known gives us reason to believe that future investigations will add considerably to their number. In the Adelsberg, Lueg, and Magdalena grottoes, which form but an inconsiderable part of the extensive cavernous regions of Carniola, seven exclusively subterranean insects, one spider, two scorpionides, one millepede, two crustaceans, one snail, and one reptile—in all fifteen different species of animals, belonging to no less than six different classes—have been found. [Illustration: LEPTODIRUS HOCHENWARTII.] Among these dwellers of the dark, warfare is as rife as in the regions of light. Thus, in the recesses of the Grotto of Adelsberg, the cavern beetle (_Leptodirus Hochenwartii_) is persecuted and devoured by the scorpioniform _Blothrus spelæus_, and by the eyeless spider (_Stalita tænaria_). The black and brown Leptodirus discovered in the Grotto of Adelsberg in 1831, by Count Hochenwart, is distinguished by long and delicate antennæ and legs, and comparatively small translucent and smooth elytra. The unique specimen found at the time was unfortunately lost, and although twenty-five florins were offered to the cavern guides for one of these beetles, fourteen years passed before it was re- discovered in the same cave. Since then other collectors have been more fortunate, particularly Prince Robert Khevenhüller, who, during his repeated visits to the Cave of Adelsberg, captured no less than twenty specimens of the Leptodirus. Cautiously feeling its way with its long antennæ, the beetle slowly ascends the damp stalactital columns, and accelerates its movements at the approach of a light. The greater number were found in the evening, thus giving reason for supposing that the Leptodirus is a noctural beetle, although it is hardly possible to conceive how the alternating influence of night and day can still be felt in these regions of darkness. The manner in which it is pursued by the eyeless Blothrus (discovered in 1833, by Mr. F. Schmidt), has been several times observed by Prince Khevenhüller. He once saw one of these cavern scorpions slowly crawling along, stretching out its palpi in all directions, and evidently on the search. He immediately guessed that the animal was engaged in a hunting expedition, and soon found that he was not mistaken, for a fine Leptodirus was crawling about four feet higher on the opposite wall. For a long time the Prince left the two insects undisturbed, until he had thoroughly convinced himself that the movements of the Blothrus were evidently regulated by those of the Leptodirus, and that the former was, beyond all doubt, in pursuit of the beetle. A Leptodirus having been thrown along with a Blothrus into a phial, was immediately cut to pieces and devoured.