244: MR. H. H. THOMAS ON THE [^Ug. I909, 



Fig. 3. Anatase, steeply pyramidal, with small basal plane, from the Pebble- 

 Bed of Woodbury Castle (South De\on). X about 150. (See 

 p. 232.) 



4a. Staurolite, an almost perfect crystal showing the forms {010}, {llO}, 

 {lOl}, and {00l}, from the recent blown sands of Newgale 

 (Pembrokeshire). X 100. (See pp. 234-35.) 



4 b. Staurolite, similar crystal to the foregoing, from the Pliocene deposits 

 of Lenham (Kent). X about 100. (See pp. 234-35.) 



4 c. Staurolite, grain bounded by cleavage-faces, the most usual mode of 

 occurrence in the Peel rocks of the West of England and the 

 Midlands, from the Pebble-Bed of Budleigh Salterton (Devon). 

 X about 100. (Seep. 234.) 



5. Anatase, imperfect octahedral crystal with moderately large basal plane, 

 from the Lower Breccias of the Parson and Clerk Rocks, Teign- 

 mouth (Devon). X about 150. (See p. 232.) 



6 a, b, c. Tourmaline, blue hexagonal crystals flattened parallel to the 

 base, and modified by narrow rhombohedral planes, from the Lower 

 Sandstones of Monkerton, near Pinhoe (Devon). X about 100. 

 (See p. 233.) 



7. Anatase, tabular crystals growing on decomposing ilmenite from the 

 Keuper Sandstone of Weston (Cheshire). (From a preparation 

 supplied by Mr. J. B. Scrivenor, M.A., F.G.S.) X about 100. 

 (See p. 232.) 



Discussion. 



Dr. J. W. Evans laid stress on the importance of work on sand- 

 grains. He suggested that the tabular crystals of anatase might 

 be cleavage-plates following the perfect basal cleavage. 



Mr. G. Barrow remarked on the interest of the Author's table 

 showing the distribution of the minerals at different, horizons. In 

 the lowest beds, blue schorl-needles seemed especially abundant ; 

 these were of local origin, as one would rather expect. Higher in 

 the series staurolite became common ; but this mineral was not of 

 local origin, being possibly derived from the rocks in which the 

 adjacent English Channel (clearly a submerged valley) had been 

 cut. These rocks were almost certainly, in the main, pre-Cambrian 

 and metamorphosed. There was a possible doubt as to the origin 

 of the garnets : their local source, in part at least, would be proved 

 by the presence of the pneumatolytic type, with the characteristic 

 well-marked banding, or parallel planes of growth. Were such 

 garnets found in the sediments examined by the Author ? 



The Peesident (Prof. Sollas) complimented the Author on the 

 successful manner in which he had brought the skill of the minera- 

 logist to bear on the interpretation of these minute constituents 

 of sedimentary beds. The paper was of interest, not only for its 

 numerous observations in detail, but for its general conclusions ; 

 and he would like to enquire whether the Author still looked to 

 Armorica as the source of some of the minerals that he had 

 determined. 



The Author thanked the previous speakers for their kind remarks 

 relative to his work, and, in reply, stated that although in some 

 instances tables of anatase might be produced in the manner 



