Sollas— On Soda-Granites and Associated Dykes of Wicklow. 271 



1. Soda granite from Cuslibawn Hill (Haughton). 



2. Quartz keratophyr from the Harz (Teall, /. c.). 



3. Soda granite from Coolboy (Teall, /. c.). 



4. Keratophyr from the Fichtelgebirge (Teall, /. c). 



In the soda-granophyre of Croaghan-Kinshella we have CaO, 

 0-89, Na 2 0, 5-58, K 2 0, 0-40. 



The mineral constitution of these rocks is very similar, except 

 that so far I have not been able to determine the presence of either 

 augite or hornblend in the soda granites, and one or other of these 

 minerals appear to be an essential constituent of keratophyr. It is 

 by no means certain, however, that some of the mineral which 

 appears to be epidote may not prove to be the missing constituent. 

 I may note that the illustrations of quartz kersantite, 1 given by 

 Barrois in his geology of Asturia, "Asturies de Galicie " (plates 1 

 and 2), suggest a resemblance to the soda-granite of Aughrim and 

 Coolboy, except for the very manifest augite or amphibole which 

 the former contains. 



NOTE ADDED IN THE PEESS. 



The supposed species of epidote is, as I had imagined, a variety 

 of allanite ; and augite is certainly not present in the rocks. 



1 According to Eosenbuseh (Mikroskopisch Physiographic, p. 337), this quartz 

 kersantite should be regarded as a diorite-porpbyrite. 



