478 Correspondence — Professor T. G. Bonney. 



the base of the Edge coals of Midlothian. These coals may there- 

 fore exist beneath the sea under conditions which will enable them 

 to be worked at some future time. 



But the most striking addition to our knowledge of the 

 Carboniferous rocks of Scotland is that furnished by Mr. Kidston's 

 examination of a large suite of plants from the Canonbie Coalfield, 

 in the collection of which he was assisted by Mr. Macconochie. 

 This proves that Upper, Middle, and Lower Coal-measures are here 

 present. According to Mr. Kidston the highest measures are on 

 the horizon of the Eadstock Beds, an horizon which is higher than 

 any reached in the midland or northern coalfield so far as is at 

 present known. 



The Permian and Trias, the Jurassic and Tertiary deposits have 

 also received attention during the past year, but we cannot now 

 dwell with greater detail on the Summary before us, which deserves 

 to be more fully studied by all who take an interest in the progress 

 of geology in the British Isles. 



coI^I^Es:poI^^3D:EI^^GE!. 



COMMENTS ON A COMMENTATOE. 



Sir, — As my name has been made prominent in more than one 

 part of the last number of the Geological Magazine, permit me 

 to say that I see no reason to modify what I said (1895, p. 75) 

 about the Budleigh Salterton pebbles, and cannot admit that 

 Mr. Shrubsole is right in asserting the oblate spheroidal form to 

 have been acquired by rolling on the beach. To this point I paid 

 particular attention, with what result may be seen in the following 

 extract from my diary. After some notes on size, form, and colour, 

 it goes on — " I think these peculiar, almost semicircular ellipsoids 

 are rather commoner on the beach than in the cliffs, perhaps due 

 to their being a little more worn and selected. Nevertheless, they 

 are generally the dominant form in the sections, but are less 

 conspicuous from being half buried." This flattened form could 

 not be acquired by wave-action alone, but must be initiated by 

 a certain original ' slabbiness ' in the rock from which the pebbles 

 have been derived. A parallel to this may be found in the flattened 

 chalk pebbles on the beach in the Bridlington district. Thus the 

 dominant quartzite pebbles at Budleigh Salterton must have come 

 from a source difierent from that which has supplied most of those 

 at Cannock Chase. 



Reference is also made to a paper of mine on Luxulyanite. It is 

 not easy to disentangle the writer's meaning from the mass of 

 irrelevant matter, but I presume it is not meant to be complimentary, 

 so I may say that though more than a quarter of a century has 

 passed since I wrote this paper, and I have studied many tourmaline- 

 bearing rocks in the interval, I have found no reason to alter the 

 opinion then expressed as to the history and formation of this 

 mineral in that case. I also am familiar with party-coloured 

 crystals of tourmaline, but fail to see that their occurrence affects 

 the accuracy of my original conclusions. I do not remember having 



