Page:The New International Encyclopædia 1st ed. v. 04.djvu/440

* CAVE. 376 CAVE ANIMALS. held various ecclesiastical appointments, among Iheiu tlie rectory of Allhallows tiie (ireat, Lon- don, liis fame rests on his voluminous writ- infs on CUuich history, the most important of whiuli arc: I'limilirc Vhrisliuiutij (Kir.;); IJcts of the Apostles (U>7(i); Lilts of llie Fatherx (1077); and Hcriptorum Eccksiastivi/rum His- loriu Literuria (1088-98), which were once stan- dard works. CAVE ANIMALS. A name given to a peculiar assomblaije of animals livinj; in the total darkness of caverns. Cave animals usually differ from their epigisan or out-of-door allies in being blind, and either partially or totally eyeless ; in having the loss of sight compensated for by greatly developed feelers and other ap- pendages, or by tactile hairs, ami in being whit- ish or colorless, the coloring matter or pigment in the skin having undergone degeneration. Cave F.un,e. The ricliest cave faunaj occur in southern France, in limestone deposits near or at the base of the Pyrenees, though the great grotto of Adelsberg, near Triest, is the classic abode of caveniieolous forms, including the bliml triton, eyeless beetles, etc. In North America Mammoth and Wyandotte eaves, 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 Crustacea 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 iu caves and wells in New 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 us consider the conditions under which these blinil animals live. The total length of the avenues is about I.'jO 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 seantj-, and the animals are all carnivorous, jneying on one another. The temperature is very equable, the mean for the winter months being 53° F., and for the sum- mer rA" 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 caves about forty or fifty more, while there are several hundred kinds existing in European caverns. Bi.ixi) FisiiKs. The most striking and inter- esting form in Mammoth Cave is the blindfish {Ambli/opsis spelii'.us). It is about four inches long, pale or colorless, blind, the eyes being vestigial. According to Prof. C. H. Eigenmann, who has made the latest and most thorough studies on this and other blind fishes, Amblyop- sis seeks the dark and shuns the light. A ray of light or a lighted match will cause them to dash away, and bright sunlight appears to be irritating ; if exposed to it, the fishes swim about uneasily. In well-fed adult specimens there is no external indication of an eye : but in young ones, before reaching a length of two inches (oO mm), the eyes can be distinctly seen, owing to their pigment, which is lost in the adult. The optic nerve can be traced in examples under an inch (25 mm.) in length, but in larger specimens "it is no longer possible to follow the nerve to the brain." In only one instance could Eigenmann trace the nerve into the brain-cavity. The lens is much reduced, and, in fact, the vestiges of the eyes are exceedingly variable, "in striking contrast to the condition in normal fishes" (Eigenmann). This will apply to the eyes of other blind fishes and blind in- sects, Crustacea, etc. While the sense of sight is lost, that of touch in the blind fish, as in most other cave animals, is exalted. Amblyopsis is provided with series of tactile papilhe, arranged in ridges on the front and sides of the head. Though the ears of this blind fish are said by Wyman to be largely developed. Dr. .Sloan, who kept several of these fishes in an aquarium for twenty months, states that they "manifested total indifference to light and sound." They are said to show in their movements extreme timid- ity and caution. Eigenmann has proved that, contrary to early views, Amblyopsis is not vivi- parous; the eggs, however, are laid by the fe- male under her gill-membrane, and the breeding period extends at least from the first of March to November. The young feed on minute crus- taceans and other microscopic animals, and the older ones feed greedily on the blind ascllus (CiBcidotaia). Like all other cave animals, the body is colorless, and the blind fishes glide through the aquatic shades like " white aquatic ghosts." There are four other species of blind fishes, and with Amblyopsis is associated Tt/ph- lichthi/s xiihterriineux, which lives in caves east of the Mississippi, while Tiiphlictithijs rosie in- habits caverns west of this river. Sulitcrraneau Salamanders. — A still higher type of vertebrate, two species of salamanders, have become adapted to cave life, losing their eyesight by disuse. The species of the genus Spelerpes frequent damp, dark situations and the entrance to caves. An allied form (Ti/phlo- triton spela'us of Stejneger) is distinctly a caver- nicolous as distinguished from a twilight species, and has never been found outside of caves. Its eyes show early stages of degeneration. It in- habits caves in southwestern Missouri, and oc- curs under rocks in and out of water. Still another salamander, whose eyes are the most de- generate known among amphibians, is the Tiiplilomnliie Rdthtmni of Stejneger. It lives in subterranean streams, tapped by an artesian and. also a surface well, near .San Marcos, Tex., and likewise occurs in one of the caves near that town. Its remarkably long and slender legs are too weak to support its body when out ol water. The eyes of this salamander are in many respects much more degenerate than those ol the Proteus of Austrian caves. It has no eye- I