34 Thi Irish Naturalist. 



separated from a species found in the caves of Carniola, and 

 the Sinella is almost identical with one inhabiting the caves 

 of North America ; while the spider is apparently the same as 

 a cave-dweller from the Mediterranean district of southern 

 France, which probably occurs in the North American caverns 

 also. Had we to do with animals of the upper fauna, these 

 results, though highly interesting, would not be without 

 parallel in species alread}^ known. The identity of certain 

 Irish animals and plants with south European (Pyrenean and 

 Mediterranean) forms has long been one of the most marked 

 peculiarities of our fauna and flora ; while we possess at least 

 a few North American plants found nowhere else in Europe. 

 But the occurrence of cave-dwelling species with so wide a 

 range is a truly remarkable phenomenon. The caves cannot 

 be of any great geological age. Any possible geographical 

 connection which would permit the migration of subterranean 

 animals between southern Europe and Ireland, or between 

 Ireland and North America seems altogether out of the 

 question within any period- during which the fauna can have 

 been .specifically identical with that of the present da}^ The 

 onl}" conclusion is that from ancestors, presumably of the 

 same genus, which took to an underground life in such 

 widelj^-separated localities, the similar conditions of the caves 

 have evolved descendants so similar that when compared, 

 they cannot or can hardly be specifically distinguished from 

 each other. Should the identifications suggested in this 

 paper stand the test of a comparison of t3'pes, we shall have 

 proof that the independent development of the same species, 

 under similar conditions, but in widely distant localities, has 

 taken place. It must be granted, however, that cave-con- 

 ditions are so marked and exceptional, that it might not be 

 safe to argue from them as to what may have occurred in the 

 upper world. 



With the exception of Mr. F. Cambridge's record of 

 Porrhomina egcria from the Wookey Hole, I am not aware 

 of the observation of members of the subterranean fauna in 

 an}^ British cave except Mitchelstown. It seems almost 

 certain that a careful search would reveal further localities 

 and new species. The great development of the Carboni- 

 ferous I,imestone area in Ireland, and the number of caverns 

 known to exist in the formation, marks the country out as 



