326 BRACHIOPODA OF THE 



Cornwall they must be identified first, and cooked up for pebble purposes afterwards. 

 As far as a derivation from the Hangman Grits zone, in which, by-the-bye, fossils are 

 extremely rare, it is not even theoretically admissible imprimis. The Budleigh pebbles 

 proper are replaced by local materials somewhere about the latitude of Burlescombe ; 

 and the bed at a few miles further passes into hard conglomerate, local limestone, and 

 grit pebbles. This hard conglomerate with local fragments is the sole representative of 

 the pebble division in the only part of North Devon and West Somerset area where we 

 can say the Hangman beds were exposed to Triassic waters, i.e. the Bridgewater and 

 Willeton areas ; yet it is very uncertain, even in these, whether Hangman beds were 

 exposed so early as the commencement of the ' Keuper,' the age I assign to the 

 Budleigh-Salterton beds. The general character of the Hangman Rocks is unlike that 

 of the fossiliferous pebbles of Budleigh, but I dare say that many of the numerous 

 unfossiferous varieties of pebbles in the bed might be paired with specimens from 

 Hangman and Foreland Rocks, which would be no proof of derivation from them ; and, 

 indeed, I find it not the least arduous of my duties about here to draw the distinctions 

 between grits of different ages, which although nature has broadly distinguished in 

 general characters, it seems at times as though she had forgotten to cleanse the old 

 tints from the brush or change the stippling of her textures." 



In another letter Mr. Ussher enters into long details to show that it was not possible, 

 or at all probable, that the Devonian element of the Budleigh-Salterton pebbles could 

 have come from rocks situated in the Foreland coast. 



With respect to the supposed derivation from Smuggler's Cove, Torquay, Mr. 

 Tawney, in a paper published in vol. vii of the ' Geological Magazine,' states that 

 that assumed source of derivation must be given up. 



With regard to the other Devonian rocks in situ in Devonshire and Cornwall, there 

 exists no evidence that I can see as to their having contributed to the mass of Budleigh 

 Salterton pebbles. It is therefore evident that one must seek out of England for rocks 

 that may have furnished the element of the Budleigh pebbles. In the sequel we will 

 again revert to this subject when treating of the Normandy and Brittany sources. 



2. The assumed British Silurian Source of Derivation. 



The Lower-Silurian Rocks of Cornwall have been described by Sir H. de la Beche, 1 

 the Rev. A. Sedgwick, 3 and others, 3 to whose works the reader is referred. Mr. 

 Collins states in his memoir already quoted that the Lower- Silurian Rocks of Cornwall 



1 1839. Beport on the Geology of Cornwall, Devon, and West Somerset. 



2 1852. On the Slate Rocks of Devon and Cornwall, with List of Fossils, by Prof. M'Coy— Quart. 



Journ. Geol. Soc., vol. viii, Feb., 1852. 



3 1841. Phillips. Figures and Descriptions of the Palaeozoic Fossils of Cornwall, Devon, and West 



Somerset. 



