MELAPHTRES AND FEL8ITES OF CARADOC. 543 



foregoing paper I have, therefore, endeavoured to supply some of 

 the proof which seemed, hitherto, to be wanting. 



VI. SurrLEMENTARY NOTR. 



When this paper was read I was not aware that Prof. Lapworth 

 had been devoting his attention to the eruptive rocks of Caradoc 

 and its neighbourhood. In the discussion which followed, Sir 

 Archibald Gcikic alluded to the detailed map which Prof. Lapworth 

 had constructed and of the existence of which I was unfortu- 

 nately ignorant. 



On writing to Prof. Lapworth he most generously gave me a large 

 amount of valuable information relating to his work and forwarded 

 his unpublished map to mo for inspection. The latter is, unques- 

 tionably, a very careful and detailed piece of surveying : a map 

 which, when published, will be the most important exponent of the 

 geology of this district which has ever appeared. On it the basic 

 rocks and rliyolites are duly recognized, while the boundaries of 

 many intrusive sheets which, in my brief examination of the ground, 

 passed unnoticed b}' me, are laid down. 



It is only just that I should take this opportunity of bearing 

 testimony to the splendid work which Prof. Lapworth has done, and 

 is doing, in this district, and I would also gratefully acknowledge 

 his courtesy in so readily communicating the result of his labours. 



EXPLANATION OF PLATE XIX. 



Fig. 1. Vesicular melaphyre (altered vesicular basalt-glass). S.W. side of Oaer 

 Caradoc, near the top of the hill. X 30 linear. 



2. Ditto, X 140, showing corroded felspars. 



3. Melaphyre (amygdaloidal), showing pilotaxitic structure. S.W. side of 



Caradoc, about 100 feet below the Camp. X 45. 



4. Melaphyre tuff (altered vesicular basalt-glass tuff). SW. side of 



Caer Caradoc, at the top of the hill. The broad, pale, diagonal band 

 represents cementing material, X 18. 

 .5. Perlitic felsite (deviti-ified obsidian). Above Caradoc Coppice, S. end 



of Caradoc Hill, N.W. flank. X 45. Crossed nicols. 

 (5. Portion of the section represented in figs. 1 and 2, showing a pseudo- 



morph of magnetite after olivine. X 140. 

 7. Portion of the section represented in figs. 1, 2, and 6, showing skeleton 

 crystals. X 75. 

 Figs. 1, 2, 6, and 7 are from specimen No. XII. 

 Fig. 3 is from specimen No. X. 

 Fig. 4 „ „ „ No. XIV. 



Fig. 5„ „ „ No. 11. 



Discussion. 



The President aUuded to the detailed mapping of the Caradoc 

 region by Prof. Lapworth, which, though not yet published, was 

 known to many Fellows of the Society, and included the recognition 

 of rhyolites, rhyolitic tuffs, and basic sheets. He believed that the 

 views of Prof. Lapworth and Mr. Rutley would be found to be 

 in the main accordant. 



Prof. BoNNEY also spoke. 



