BLIND Pp.:1'•s. The most striking and inter esting form in Mammoth t'ave is the blindfish (A nib/ apsis spek us). it is about four inches long, pale or colorless, blind, the eyes being vestigial. According to Prof. C. II. 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 thorn' 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 ; hut in young ones, before reaching a length of two inches (50 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 papilla', arranged in 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 "maniffsted 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. parons; 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 asellus (Cateidotma). 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 Toh lichthys subterrant us, which lives in eaves east of the Mississippi, while Typhlichthys in habits caverns west of this river.
Subterranean Sala manders.—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 (Tliphlo triton spelaws of Stejneger) is distinctly a caver nicolons 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 Typhlamolye Rathbuni of Stejneger. It lives in subterranean streams, tapped by an artesian and also a surface well, near San Mareos, 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 of water. The eyes of this salamander are in many respects much more degenerate than those of the Proteus of Austrian caves. It has no eye muscles, the retina is more reduced, no trace of the lens could lie found except in one individual, and no blood-vessels enter the eye. the shape of the eye itself, which lies just beneath the skin, being very variable (Eigenmann).
The Proteus of Adelsberg Cave is a salaman der-like form, allied to our mud-puppy (Nee th•us). It has external gills. very weak legs, ending in three toes in the fore and two in the hinder pair. Its body is remarkably slender, white or colorless, and the eyes are minute, just visible beneath the skin. It is noticeable that when this animal is kept in the ex posed to daylight, the stimulus of the light-rays causes the pigment to develop so that the skin turns slightly dark.