Yol. 65.] CARBONIFEROUS LIMESTONE OF COUNXZ CLAEE. 539 



Mapping, at that time, was executed by sole reference to the 

 lithological characters of the rocks, and little attention seems to 

 have been paid to their fossil contents. The evidence, now adduced 

 by a study of the latter, necessitates very little alteration in the 

 subdivision, the main line of division between the Lower and Upper 

 Limestones of the Survey being found to correspond with the 

 transition from a Tournaisian to a Visean fauna. It will be shown, 

 however, that the Lower Limestone Shales are not separable, as 

 mapped at present, from tbe Lower Limestone, and that the Middle 

 Limestone, or ' Calp ' of other districts which is not recognized here, 

 may still on palaeontological grounds be readily distinguished from 

 the Upper Limestone. 



The meagre fauna hitherto recorded from the limestone of County 

 Clare is, I think, due to certain adverse conditions which the nature 

 of the country presents. In the north and centre of the county, 

 the bare surface of the rock is exposed over vast areas ; and, although 

 the rainfall is considerable, it is nearly all absorbed directly and 

 carried off by subterranean channels. 1 In consequence, sections 

 afforded by river- or stream-valleys are practically absent ; and, as 

 building-material lies ready to hand on the surface of the ground, 

 quarries exposing fresh surfaces of rock are seldom available. 



The limestone is traversed by a great series of open joints or 

 ' grikes,' the edges of which become carved and rounded by solution ; 

 and fossils, which are not often visible except in the form of 

 hollow casts, are extremely difficult to extract. The sea-cliffs, too, 

 afford no better collecting-ground, for the spray has etched out the 

 limestone between high and low-water marks until it resembles a 

 great bed of scoriaceous lava, the face of which it is impossible to 

 penetrate. 



The southern part of the county is covered to a large extent by 

 drift and peat-bogs ; the beds, however, become less horizontal and 

 the stratigraphy is easier to make out, sections in quarries and 

 stream-valleys, though somewhat isolated, being comparatively 

 numerous. 



Prom the foregoing remarks it will be readily understood that 

 the description in minute detail of any one complete section, such 

 as that presented by the Avon Gorge of the Bristol area, is a 

 practical impossibility. My aim, therefore, has been to make a 

 more or less complete examination of the whole area, and determine 

 the more important details of the faunal succession ; and it is hoped 

 that the results included in this paper will show that a faunal 

 correlation can undoubtedly be made with the Carboniferous 

 Limestone of other remote localities. 



1 The amount of water carried off in this way must be considerable, and 

 solution of the limestone very rapid. During my first visit to Ballyvaghan, 

 it rained unceasingly for two whole days, but after its cessation all trace of 

 moisture had disappeared in a few hours' time. During a rainy season, the 

 sea-water of the bay is rendered brackish for some distance from shore, suffi- 

 ciently so for cattle to drink it. 



