272 Reports and Proceedings. 



as a deposit formed all at once, but, on the contrary, as a very gra- 

 dual one. Whilst tinny gravel was being deposited at the head of 

 the valley, fine silt was settling down at the lower end of the valley 

 ten or twenty feet above previously deposited tin-ground. The tin- 

 ground at the lower end of a valley may therefore have been de- 

 posited thousands of years before a similar deposit situated a mile or 

 two higher up. 



There is next to nothing to interest the palasontologist. Eemains 

 of an elephant have been found in one place in Banca in the tin- 

 ground. At the present day the elephant is living in Sumatra but 

 not in Banca. The fossil, therefore, points to an ancient connection 

 between the two islands. The following summary is good : — 



'•' ] . The stream-tin of Banca is derived from the granite and the 

 rocks that surround it to a distance of nearly two miles. 



"2. The valleys and tributaries' which take their rise in these 

 rocks, and also the plains close by them, carry stream-tin ; but the 

 valleys which are found elsewhere contain no tin. 



" 3. A deposit of tin derived from one source seldom extends further 

 than two miles along a valley." 



On the whole, the work forms a useful addition to our knowledge 

 of the geology of the Indian Archipelago, and persons interested in 

 tin will find plenty of details concerning the working and smelting 

 of the stream-tin of Banca. 



Gbological Society of London. — April 17th, 1867. — Sir 

 Charles Lyell, Bart., M.A., F.E.S., Vice-President, in the chair. 

 The following communication was read : — 



" On the Physical Structure of North Devon, and on the Palseon- 

 tological Value of the Devonian Fossils." By Eobert Etheridge, 

 Esq., E.E.S.E., F.G.S., Palaeontologist to the Geological Survey of 

 Great Britain. 



The Lower, Middle, and Upper groups of sandstones and shales 

 of West Somerset and North Devon were described in this paper as 

 occurring in a regular and unbroken succession from north to south ; 

 namely, from the sandstones comprising the promontory of the Fore- 

 land, at the base, to the grits and slates, etc., overlying the Upper 

 Old Eed Sandstone of Pickwell Down to the South. The author was 

 tmable to see any traces of a fault of sufficient magnitude to invert 

 the order of succession, or that would cause the rocks of the Fore- 

 land at Lynton to be npon the same horizon as those south of a line 

 of high ground that passes across the county from Morte Bay on the 

 west to Wiveliscombe on the east. 



The Foreland grits and sandstones are overlain by the Lower or 

 Lynton slates, and form a group equal in time to the Lower Old 

 Eed Sandstone of other districts, but deposited under purely marine 

 conditions. 



' There is evidently a word left out here. The sentence should doubtless stand 

 thus : " The valleys of rivers and their tributaries," etc. 



