The lower animals tell the same story of de generation. blindness and total or partial atrophy of the eye, together with loss of color, and. in a more striking way. the compensation for the loss of vision by a great increase in length of the and other appendages, or the growth of long, slender tactile bristles.
Blind Crayfish and Insects.—.1 notable in habitant of and other eaves is the blind crayfish (Or•oncetes pellu•idusI. It dif fers from its out-of-door allies in being blind, slender-bodied. and colorless. The eyes' arc pres ent, hut they are much reduced in size and destitute of a cornea and of black pigment. while the colorless body is slender. It is not only blind, but deaf. as A. S. Packard discovered that the auditory saes are a third smaller, and the auditory hairs in the ears also a third shorter and smaller: hence it is to be inferred that the ears of the blind crayfish are degenerate, and the sense of hearing nearly, if not quite, obso lete. This creature is also exceedingly timid and cautious in its movements.
The eyeless beetles of caves (Anophthalnms) have no vestige of eye or of optic nerves and ganglia; hut in their movements they closely resemble their epig;can allies. While their bodies and appendages are slender. they grope their
way about by means of very long tactile bristles. They act exactly as if enjoying good eyesight. They walk, run. stop to explore the ground, seek their food, and run from the fingers of the in sect-hunter who tries to seize them with the same agility as beetles provided with eyes. Other beetles, such as which has re tained vestiges of the outer eye; some spiders, comprising an eyeless species, and others with eves varying in size. some much reduced, spin little webs MI the walls of the chambers. Anamg the harvestmen sonic have extraordinarily long legs; while the Campodea, a wingless insect of the Mammoth and other caves both of the States and Europe. differs from the outdoor form in it- :interline and abdominal appendage, being greatly exaggerated in length. The cave crickets have eyes, but they do not extend into the re moter parts of the cave. and hence are twilight species. and probably cross with other twilight individuals. Besides these, there are many eye crustacea of different group,—mites, myria pods, primitive wingless insects, a few flies, worms. and infnsoria which go to make up this assemblage of sightless troglodytes.