lOo The Irish Naturalist. i April, 



(i.) Species inhabiting the entrances to caves, near the 

 light, Ui^ing the cave as a convenient hiding-place \ such are 

 the two vSpecies of Mda, perhaps Lcptyphantcs pallidus, and the 



bats. 



(ii.) Species which have wandered into the caves, accident- 

 ally, perhaps, or have been washed in by floods, and are so 

 to speak " fish out of water;" examples of such are the water- 

 bugs and crane-flies from Bohoe ; lulus, Velia, Sciara and the 

 beetles from Coolarkin ; Clivina fossor from the Marble Arch ; 

 and the frog, Pterosticlms, Sciara, and Ancyrophorus from 

 Mitchelstown. 



(iii.) The Troglodytes; only found in Mitchelstown, e.g, 

 Lipura, Sinella and Porrhoma my ops. 



(iv.) Those species which do not fall under any of these three 

 groups seem to me to form a division intermediate in position 

 betw^een the last two, and in most cases inhabiting caves 

 which present conditions intermediate between Bohoe and 

 Mitchelstown caves, which I may safely take as the extremes 

 of my series. Such are Tomoccrus tridaitiferus, Brachydcsvms 

 supeyus, and Porrhoma miaophthalma, which seem to be 

 equally at home above ground and underground. These 

 creatures seemed quite at home in Coolarkin, and the dry 

 part of the Marble Arch cave, and I see no reason to doubt 

 that Brachydcsmus and his companions in darkness may have 

 lived and multiplied there for many generations, undisturbed 

 by any such catastrophes as the floods that characterize 

 Bohoe cave. 



While fully aware of the great gap that exists between a 

 cave-fauna of this type and that of Mitchelstown, I see no 

 reason to doubt that at one time the Mitchelstown fauna 

 was one somewhat of this type, consisting of a few unwary 

 animals which got into the cave and had to make the best of 

 it ; the isolation and probably much greater age of the 

 Mitchelstown fauna may account for their specialization ; and 

 if 'SO, provided that among the many unexplored caves of 

 Ireland we can find some presenting conditions intermediate 

 between those w^e find in Coolarkin and in Mitchelstown, we 

 may almost hope to fill up some of the gaps in the history 

 of the evolution of cave-faunas. 



