GENERAL CONSIDERATIONS. 



93 



applies equally well to the food, each species taking the same food as 

 its epigean relatives. Attention has been called to this fact throughout 

 the paper. Anopthalmus is closely related to the genus Trechus, whose 

 almost innumerable species in Europe are much given to living in deep 

 crevices in the earth or under large stones, not to mention about 60 

 species of this genus which frequent caves. Species of Platynus live 

 in damp places in ravines and under stones along streams. Species of 

 Qaedius live in damp, shady places, as do also the members of the 

 dipterous family Helomyzidae. Psychoda, outside of caves as well as 

 within caves, lives under debris and its larvae are upon decaying matter. 

 The spiders Phanetta suhterranea, Willibaldi cavernicola, and Erigone 

 infemalis live under stones in the cave, spin little or no web, and feed 

 upon decaying organic matter, or catch their prey by springing upon it. 

 They have outdoor relatives which live in the same retired situations 



Decaying 

 organic 

 matter 



Earth worms, etc 



Fungi — Thysanura 

 Diptera 

 Mynapoda 



Coleoptera 



(in part) 



Ceuthophi 

 Cyclops 



Crangonyx 

 Caecidotea 



Spelerpes \ 



— '^Perotnyscus 



Larger Mammals 

 (on all ttie others) 



Amblyopsis 



Cambarus 



Fig. 13.— Table of food relations of cave species. Reading from right to left the lines 

 leading from Peromj/scu* indicate that it may feed upon decaying matter as well 

 as all other animals in the cave, except those indicated in the lower part of the 

 figure. Earthworms feed upon decaying organic matter, and in turn are fed upon 

 by Spelerpes and Peromyscus. 



and feed in the same manner. On the other hand, Theridium kentucky- 

 ense, T. porteri, and others which live near the mouth and spin snares 

 to catch their prey either themselves live outside of caves occasionally 

 or have near relatives which live outside and likewise spin snares to 

 catch prey. The cave species spin the web characteristic of the family. 

 The Ceuthophilus, in its habit of occasionally going under stones and 

 generally staying in cracks and crevices in the cave, shows a close 

 approach to the habits of the same species when living outside of caves 

 and to the habits of its relatives which live in caves, about wells, under 

 logs, and in the dark parts of cellars. The same thing is true of the 

 myriapod Conotyla bollmani and the thysanuran Sinella cavernarum, their 

 relatives outside generally living in damp places under logs, leaves, etc. 

 This list of illustrations might be considerably increased. The similarity 

 of habits of concealment, of obtaining food, and of rearing larvse which 



