56 MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES. 



it is oval and somewhat flattened. The body is white, the appeudages being slightly dusky. The 

 eye prominence is rather large compared with that of N. troglodytes Pack. The eyes are wanting, 

 the pigment being colorless, but with a dark line indicating the traces of a retina. Chelicerae 

 slender, rather long, the inner edge of each finger with short, stiff setae; on the upper side, at the 

 base of the immovable finger, are two straight, stiff hairs ; the hand is not setose, as in that of 

 N. troglodytes. The pedipalps are only of moderate length, being, in proportion, only about one- 

 third as long as those of 2V. troglodytes ; the second joint is not much longer than the basal, being 

 slightly longer than thick ; third joint three times as long as the second ; third and fourth of the 

 same length, but the fourth a little thicker] fifth slightly longer and thicker than fourth, with 

 numerous stout setae of nearly even length; sixth (terminal) two-thirds as long as the fifth and 

 nearly as long in proportion as the terminal joint in JV. troglodytes ; it is very setose aud the tip 

 is rounded. Legs of second pair 3 mm in length, hairy, last tarsal joiut undivided; fourth pair 4 mm 

 in length, the last tarsal joint with nine subjoints, and the ungues smaller than in the second 

 pair. 



Length of the body, including the cheliceres, l mm 



Locality, Bat Cave, Carter county, "Kentucky. 



The specimens found were immature, but the species is so characteristic that I have ventured 

 to describe it. It differs from the Utah 2V. troglodytes chiefly in the much shorter pedipalps, with 

 proportionally much shorter joints in its naked hand and much slenderer legs. The specific 

 name is given it in allusion to its feebly-developed, degenerate eyes. It is the first species of the 

 genus known to occur in the eastern United States. 



AEANEINA. 



It is in the small caverns of Carter county, Kentucky, and the two Weyer caves (Weyer's 

 and the adjoining Cave of the Fountains), which are often but a few (less perhaps than a hun- 

 dred) feet below the surface, that the variation and number of species of spiders is greatest. In 

 each set of caves there are three species to oue in Mammoth and Wyandotte caves. The individual 

 variation was the greatest in Nesticus pallidas, aud, as might be suspected, iu the eyes. The 

 degree of variation is indicated in Mr. Emerton's description. 



The spiders occurred more abundantly iu all the caves than we expected. The individual 

 abundance was greater in the smaller caverns, especially the Weyer caves, than any others. In 

 the Mammoth Cave the Anthrobia occurred under stones in dry, but not the driest, places on the 

 bottom at different points in the cave. Sometimes two or three cocoons would be found under a 

 stone as large as a man's head. The cocoons were orbicular, flattened, an eighth of an inch in 

 diameter, and formed of fine silk, and contained from two to five eggs. They occurred with eggs 

 in which the blastodermic cells were just formed April 25. The eggs were few in number and. 

 seemed large for so small a spider, being T |f F inch in diameter. The chorion is very thin and 

 finely speckled. The blastodermic cells seemed very large, the largest measuring nearly Tl ^ inch 

 in diameter. They were rouud, not closely packed, and showing no indications of being polygonal. 

 They all had a dark, very distinct nucleus. I was unable to trace the development of the young 

 and ascertain if the embryos are provided with rudimentary eyes. Two young Anthrobiae hatched 

 out May 3 in my room. The whole body, including the legs, is snow-white, with the legs much 

 shorter than in the adult. The adult in life is white, tinged with a very faint flesh color, with the 

 abdomen reddish. In some specimens the abdomen has beneath several large transverse dusky 

 bauds. The Linyphia subterranea, as observed living in Wyandotte Cave, is pale pinkish, horn- 

 brown on the thorax and legs, while the abdomen is dull honey yellow. 



What constitutes the food of these diminutive, weak, sedentary spiders I can not conjecture, 

 unless it be certain minute delicate mites or young Podurae. They spin no web, though some of 

 the spider's in Weyer's Cave (Cave of the Fountains) do spin a weak, irregular web, consisting of 

 a few threads. The Sciarae and Chironomus are too large aud bulky to be captured by them. The 

 probable insufficiency of food as well as light may account for their small size and feeble repro- 

 ductive powers. The individuals were far less numerous than those of the Phalangodes and 

 Chernetidae. 



