102 The Irish Naturalist. [April, 



3rd, the west side of the hall called the House of Lords ; 4th, the 

 long eastern corridor which retains, clearly marked, the traces 

 of the passage of a subterranean stream (O'Callaghan's Cave 

 and Brogden's Cave) ; 5th, and lastly, several fissures situated at 

 the south-west angle, and near O'Leary's Cave. Bach of these 

 parts is terminated by an ascending slope, ruins of vaults, or 

 rubbish washed in from the exterior, which obstruct them com- 

 pletely, as I have already seen in the ancient draining passages, 

 now stopped up, of Bramabiau, France, of Adelsberg, Austria, 

 etc. They are filled-up swallow-holes. The other fissures, 

 generally narrower, and situated in the lower parts of the 

 cave, have conducted these waters no one knows where, either 

 to some undetermined and distant outlet, or even into the 

 depths of the terrestrial shell ; they are rendered impenetrable 

 sometimes by broken pieces of stone, as at the extremity of 

 Garret Cave, sometimes by the narrowness of the clefts, which 

 become more and more contracted in the southern part of the 

 cave ; this last disposition is exactly like that of the large 

 grotto of Cro de Grandville, or of Miremont, in the Dordogne 

 (see *Xes Abinies,"^ chap, xx.), and we ask ourselves if, like the 

 latter, the cave of Mitchelstown has not served as a receptacle 

 for some great lake of ancient times, which has emptied itself 

 into it. The lowest part of the cave is, at most, thirt3'-three 

 yards below the level of the entrance, and not one hundred 

 yards as is stated in the guide book. 



The checkered disposition of the diaclases (upright joints, 

 generally perpendicular to the joints of stratification) is re- 

 markable in the southern portion (see plan) ; three sets of 

 fissures perpendicular to each other have there cut out large 

 polyhedrons of rock, often quite cubic, the right-angled 

 interstices of which have let out the waters that have gradu- 

 ally widened them out ; in depth they get more contracted 

 the more they branch out ; bCvSides they have been in a great 

 measure coagulated by the clay, which comes either from the 

 outside or from the chemical decomposition of the interior 

 rock which has become corroded. 



The Well (No. 8) marked in the Gallery of Distaffs is 

 impracticable on account of the glutinous mud with which 

 it is covered. 



'E. A. Martel: Les Abmts, Paris: Delagtave, 1894, in 4to, 570 pp., loo 

 engravings, 200 plans, and 20 plates. 



