118 OKBOYICIAX A1S T D SILURIAN OF LOUGH XAFOOEY. [June I914, 



large masses as in the Kilbride area. The relations of the rocks 

 in the Kilbride, Lough Nafooey, and Killary areas are summarized in 

 the appended table (p. 117). 



In conclusion we wish to tender our sincere thanks to Miss Gr. L. 

 Elles, D.Sc, for identifying our graptolites ; to Dr. G. J. Hinde, 

 F.R.S., for examining our radiolarian rocks ; to Dr. J. S. Flett, 

 F.R.S., for reporting on certain of our igneous rocks ; and to Prof. 

 *Gr. A. J. Cole for the gift of 6-inch Ordnance Survey maps. 



EXPLANATION OF PLATES XVI AND XVII. 

 Plate XVI. 



Fig. 1. Pillow-lava near the top of Bencorragh. 



2. Pillow-lava on the southern slopes of Bencorragh. 



Plate XVII. 



Geological map of the Lough Nafooey area, on the scale of 

 6 inches to the mile, or 1 : 10,560. 



Discussion. 



Mr. E. S. Cobbolb asked whether the other areas mentioned 

 ;agreed with that of Lough Nafooey in having the }'ounger side, so 

 far as the Ordovician rocks were concerned, on the north and west, 

 and the still younger Silurian cover on the south and east. 



Dr. J. V. Elsben remarked upon the description of certain of the 

 intrusive igneous rocks, mentioned in the paper, as lime-bostonites. 

 This type of rock was first described in detail by himself, and he 

 had applied to it the term used by Prof. Brogger for the lime- 

 bostonites of Moena. Other authors had since used different names 

 for this rock, which was, he thought, admitted to be a specific 

 type. Although he attached little importance to its actual desig- 

 nation, he did plead for uniformity of nomenclature, and drew 

 attention to the confusion arising from a want of agreement as to 

 what these rocks should be called. He presumed that the rocks 

 referred to by the Authors resembled those described in their 

 previous papers under the same name. 



Prof. Reyxolbs, in reply to Dr. Elsden, stated that the rocks 

 from Lough Nafooey described as lime-bostonites were identical in 

 character with those from Kilbride. There seemed to be lack of 

 agreement in the use by petrologists of the terms lime-bostonite 

 and keratophyre; the Authors used the former term for an 

 intrusive, and the latter for a contemporaneous, rock. 



Mr. Gtabbiner, in reply, pointed out that the lowest fossiliferous 

 Silurian beds in the Kilbride and Lough Nafooey areas were of 

 Upper Llandoveiy age, and corresponded to the lowest fossiliferous 

 Silurian deposits in the Killary district. The Arenig rocks lay 

 with the Llandeilo rocks entirely to the north of them, and the 

 Silurian rocks to the south. It was only in the extreme west of the 

 •area that the Silurian deposits came to rest upon the Llandeilo grits. 



