64 FAUNA OF MAYFIELD'S CAVE. 



stimulated by light alone, for when it got in the shadow of a small clod 

 it ceased to move. It is very susceptible to the influence of light, mov- 

 ing rapidly when the bright light is upon it and slowly or not at all 

 when it gets out of reach of the bright rays. Mechanical stimulus does 

 not cause it to move rapidly very long; it is just as effective in starting 

 the spider for a moment, but must be repeated in order to continue 

 effective. Light stimulus is effective in keeping the spider in active 

 motion as long as the stimulus is kept up, but as soon as discontinued 

 the effect decreases and disappears. 



The cocoon of this species is white, disk-shaped, and thickened in 

 the middle, and 3 or 4 mm. broad. It is attached to the under side of 

 a stone, to a piece of wood, or to the ground under debris. It is usually in 

 a slight depression which serves to shape one side of the disk. It is a 

 well-made cocoon, and while the covering of web is not very thick it is 

 compactly and smoothly made. The eggs are rather large and are few 

 in number. One cocoon examined contained but 2, another 3, another 

 5, and another six eggs. I have kept the cocoons and hatched out the 

 young spiders. The young are very light in color; abdomen white; 

 cephalothorax and legs very light gray; sternum darker with light mar- 

 gin; length when first seen 0.7 mm. The young which were hatched 

 out and kept in a small bottle spun a few threads across the bottle and 

 rested upon them. 



In Emerton's (1875, 279) specimens the colors were quite dull and 

 the front middle eyes were small. In those from Mayfield's and Truett's 

 caves some variation was noticeable in the ordinarily dull color, some in- 

 dividuals having legs and mandibles dark reddish-brown, others, includ- 

 ing a few adults and the immature ones, having little or no yellow or 

 reddish-brown anywhere. In individuals with the legs darkly colored 

 the body was also darker, but in most cases the body was very light or 

 even nearly white. There is considerable variation in the size of the 

 eyes and especially of the front middle ones which are often entirely 

 lacking. Twenty-seven individuals were studied in detail regarding 

 this point. In 2 of these the front middle eyes were about half the size 

 of the others; in 4 they were somewhat less than half the diameter of 

 the others; in 9 they were very small but fairly distinguishable; in 6 

 there was a dark blotch from which these eyes could be distinguished 

 with difficulty or not at all; and in 6 these eyes were missing altogether, 

 their location either being marked by a dark blotch or without any 

 indication of eyes or pigment. 



This species is not known to occur outside of caves and probably is 

 confined to caverns. I have taken it in Truett's Cave and have little 

 doubt that it is common in Indiana caves, although so small that it has 

 usually escaped notice. 



