398 PROCEEDINGS OF THE ACADEMY OF [May, 



cave where the three following necessary requirements are present : 

 (1) Total darkness, (2) an even temperature and (3) a saturated 

 atmosphere. In Banta's (1907) cave work and my recent paper (1911) 

 on some cave arachnids, their habitat is briefly discussed. The first 

 three species may be found from twilight localities where food is very 

 abundant and where there is a considerable range in the annual 

 temperature and a daily range in the humidity to places in total 

 darkness where insects are rather scarce, and where there is only a 

 slight range in the temperature and humidity. These first three are 

 much larger in size, all the eyes are present and they are much darker 

 in color than are the last three. The fourth and fifth species are never 

 found in the twilight, but always where the three above necessary 

 requirements occur, although most abundantly where food is com- 

 paratively plentiful. The average color is rather light and the eyes 

 are partially or totally absent. Phanetta may be found in the same 

 localities as the above two species, but furthermore it is able to live 

 in any part of a cave if the three necessary requisites are present 

 regardless of the distance from the entrance or the paucity of the 

 insect food. < )f the six species it is the smallest, lightest in color and 

 perhaps has the greatest percentage of totally blind individuals, 

 although in twenty-seven specimens Banta did not find any totally 

 devoid of eyes. Since Grammonota lives under wet eel grass in the 

 dark, its small number of organs probably can be explained in a 

 similar way. 



Now, since hunting spiders have the greatest number of lyriform 

 organs, and as these usually contain more slits than those of the 

 snarers or tube-dwellers, we must conclude that the method of cap- 

 turing food has brought about these changes in the number of organs. 



3. Discussion. 



(a) Disposition. 



Bertkau (1878) was the first to notice some isolated slits grouped 

 together and located at the distal end of the segments in Arane:r. 

 Dahl (1883) first discovered and described the transverse organ No. 13 

 on the metatarsus. Schimkewitsch (1884) was the first to observe 

 the isolated slits on the sternum but did not recognize them as lyri- 

 form organs. The next year (1885) the same author found eleven 

 organs on the legs and four on the palps of Epeira diademata, while 

 1 have obs?rved fourteen on the legs and six on the palps of Epeira 

 marmorea. Wagner (1888) first saw the two organs on the pedicle 

 and the single slits near the spinnerets, but he did not recognize them 



