Hill, BuoDiiiCK, and E,ule — The Mitchelstown Caves. 265 



Port-hole is an archway some 5 feet in height and 18 inches in width, 

 which has been divided into two openings by a stalactite. The upper opening 

 is 9 inches in diameter and the lower one about 3 feet high by 1 foot wide. 

 A fine anemolite, which will be referred to later, was met with at this point 

 (Plate XVII., fig. 3). 



The larger stalactites in the Old Cave have been described in the earlier 

 part of this paper ; the most noticeable are the Three-tiered Pillar 

 (Plate XVL, fig. 3), the Fractured Pillar (Plate XVII., fig. 2), and the Great 

 Boss in the west Chamber. 



There are a certain number of minor stalactitic formations which deserve 

 more particular notice ; these comprise the " Cave Pearls " and the 

 " Anemolites." 



The Cave Pearls. 



The (so-termed) " Cave Pearls " owe their nomenclature to Professor 

 Boyd Dawkins, who has given the only account of them extant, in his 

 book, " Cave Hunting " (p. 66). A paper on this subject was read before 

 Section C. of the British Association, at the meeting held in Dublin in 1908, 

 and can be found in the Eeport of that date. 



Cave Pearls consist of concentric layers of calcite formed around a nucleus 

 of some hard material, such as a small pebble of Yoredale rock, of limestone, 

 sandstone, or even, as in one case, of a fragment of lead ore (see Plate XVIL, 

 fig. 4). 



The method of their formation is analogous in every situation in which 

 they have been discovered. They are always found in depressions in the 

 rock — in what may be termed "nests" — into which water containing 

 calcium carbonate in solution is continually dripping from a considerable 

 height. Given the presence of a fragment of hard material, each falling 

 drop will have the tendency to turn the nucleus slightly round, and by 

 deposition to coat it with a thin film of calcite. If this process lasts long 

 enough and the deposition continues uniform, a Cave Pearl is finally formed, 

 which may range in diameter from 0*5-3'5 cm. In section such a pearl is 

 seen to be formed of the nucleus, surrounded by a great number of layers of 

 calcite of slightly varying tints of light cream or yellow. 



In the Mitchelstown Caves pearls were found in two places — in the 

 New Cave, towards the southern end of the Sand Cave ; in the Old Cave, at 

 the commencement of the Long Gallery. 



Two types were found : one of an ovoid shape, measuring about 3 cm. in 

 length and 1*5 cm. in breadth, and another about 1"5 cm. in diameter, with a 

 surface composed of from 6 to 8 facets, produced as the result of friction against 

 neighbouring pearls. In the majority of cases the nucleus consisted of 



