G. H. Kinahan — Geology of Parts of Galioay and Mayo. 453 



and lastly the felsitic base itself. Then, after consolidation, 

 chlorite, and calcite, and pyrites. 



In fine, it may be said with truth, that but for the aid which the 

 microscopic examination of thin slices of this rock affords, it would 

 have been impossible to hare arrived at a correct judgment regarding 

 its mineral composition. 

 Fro. 



Fig. 4, — fortion of polished surface of the porphyry, showing the arrangement of 

 the orthose crystals. Nat. size. 



IV. — Geology of West Galway and S.W. Mayo, Iheland. 



By G. H. Kinahan, M.R.I.A. 

 (Of the Irish Branch of the Geological Survey.) 



HAYING received permission from the Director-General of the 

 Geological Survey of the United Kingdom, I exhibited before 

 the Geological Section of the British Association at Belfast in August 

 last, the Maps and Sections of the rocks forming the hill-country of 

 West Galway and S.W. Mayo, and gave a description of the district, 

 of which the following is an epitome. 



The extreme north part of the area represented in these Maps 

 (Sheets 83, 84, 85, 93, 94, 95, 103, 104, 105, 113, and 114) was 

 surveyed by my colleague, Mr. R. G, Symes, while the rest of it was 

 examined by myself, assisted by the late Mr. Warren and Messrs. 

 Wilkinson, Nolan, Leonard, and Cruise, while Mr. Baily and his 

 assistants, Messrs. McHenry and Leeson, worked out the palaeon- 

 tology. To all the officers working under my directions I am 

 indebted for the zeal they displayed^ but especially to the late Mr. 

 Warren, who was early and late in the field, thereby losing his life 



