22 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



which are rather long and slender, acute, tipped with brown, with the anal proleg rather large 

 Legs rather long and slender; tarsi ending in a single claw. Color whitish; head and prothoraeic 

 segment slightly tinged with honey-yellow. Length, 5 mm . Three specimens, apparently not fully 

 grown, as they were small in comparison with the beetle. They were found on boards forming the 

 steps in the entrance of the cave, in perpetual darkness however, and had evidently been artifi- 

 cially introduced. 



This genus belongs to an interesting family, as the larvae of Metoecus, Rhipiphorus, Syuibius, 

 and Horia, live in wasps' nests, and Rhipidius is a parasite on Blatta germanica. The young of 

 Mordella and Anaspis, however, burrow iu the stems of herbaceous plants, while the larvae of Mor 

 della fasciata Fabr. in Europe live in the "dead wood of the poplar." 



From Alabaster Cave, California, situated in El Dorado County, Dr. Horn has described an eye- 

 less beetle, Anillus explanatus. (Trans. Amer. Enr. Soc, XY, 26, 1888,) The name of the collector 

 is not given, but on July C, 1886, Mr. E. A. Schwarz wrote me as follows regarding an alleged 

 Anophthalmus from a cave in California :* 



I have examined the Californian specimen collected hy Mr. Koebele near Sacramento and find that it is no Anoph. 

 thalmus at all, hut a large Anillus, which is possibly different from A. debilis Lee. 



THE MODE OP COLONIZATION OF CAYES. 



Not only have the Indians in prehistoric times, as is well known, frequented some of the larger 

 caves (e. g., Mammoth, Salt, Wyandotte, and Luray caves), but tracks of bears, wolves, and the 

 smaller mammals occur in most of the caves. In Luray Cave tracks and other marks of wild beasts, 

 now exterminated from the region of the cave, occur. As remarked by Mr. Hovey : 



We saw likewise, in 1878, thousands of tracks of different kinds of animals, some of which we recognized as those 

 of raccoons, rabbits, rats, and smaller creatures, while souie larger tracks seemed to have been made by wolves or 

 panthers. * * * We found also the bones of mice, rats, bats, a squirrel, and a raccoon. 



Mammoth, Wyandotte, Luray, and other caves are frequented by multitudes of bats, and 

 though several species and genera of Arthropod parasites are found on those which take up their 

 abode in caves in Europe, thus far no parasites have been discovered on our native specimens. 

 The wood-rat (Neotoma) also occurs in caves in Indiana, Kentucky, and Yirginia. In fact, as is 

 well known, nearly all caverns accessible from without are more or less inhabited by wild beasts, 

 and in this way, either by clinging to their bodies, or by adhering to the substance they may drag 

 or carry into the cave, some of the mites, false scorpions, and harvestmen may have been intro- 

 duced from the outer world. Moreover, the species of three groups of insects which are known to 

 live a more or less subterranean life in twilight, under stones or buried in the earth, may enter 

 the fissures, chasms, or sink holes, and thus colonize the caverns. The genus Trechns is a sub- 

 terranean one, its species burrowing under stones; so with the European hypogean harvestmen, 

 Phalangodes, etc., and the Myriopods. The wonder is not so much that many animals should fall 

 or be carried into or voluntarily take up their abode in caves, as that they should be able to sur- 

 vive a life in total darkness; a condition so fatal to even the lowest plant life. The fact that the 

 number of cave species of animals is so small, both in Europe and America, as compared with the 

 fauna of the upper world, shows how adverse are the conditions of life in such situations. This 

 condition, i. e., total darkness, is the barrier that forbids a number of twilight species, such as 

 Ghelifer cancroides, the cricket (Ceitthophilus stygius), Blepharoptera defessa and other flies, Quedius, 

 Polydesmus, and Lysiopetalum lactarium, Cambala annulata, and others, from becoming acclimated 

 to the darkness. 



The agency of torrents passing through the sink holes and in spring and autumn flowing 

 through the lower channels, as is the case in Mammoth Cave, is clearly sufficient to account for the 

 presence in the River Styx, of Mammoth Cave, of the eyed fishes which inhabit Green River, and 

 of Cambaras bartoni. In this way, without doubt, individuals of Asellus communis and other out- 

 of-door species of Asellus, as well as the ancestors of Dendrocoelum perccecum, were transported 

 into subterranean streams, pools, and wells, since they abound in the pools, ditches, and streams 

 throughout the country. 



* Dr. G. Marx writes me, as these pages are passing through the press, that Count Keyseiiing has described from 

 this cave a spider under the the name Usofila gracilis, but that the description has not yet been published by him. 



