BUDLEIGH-SALTERTON PEBBLE-BED. 335 



Many speculative views have been brought forward with respect to the sources of 

 derivation of those Midland-Counties Drift pebbles that contain Orthis Budleighensis and 

 Lingula Lesucuri ; but none have met the exigencies of the case. According to Professor 

 Hull's theory, the Midland-Counties pebbles were probably derived from the Old Red 

 conglomerates, no rock in situ having been discovered from which they can be traced. 

 The Rev. P. B. Brodie has also, in the ' Quarterly Journal of the Geological Society,' 

 touched upon the question ; and quite recently, in the ' Geological Magazine,' new series, 

 vol. vii, p. 404, 1880, Prof. T. G. Bonney has published an interesting paper on 

 " Pebbles in the Bunter Beds of Staffordshire." Referring to these pebbles he says that 

 two kinds of quartzite pebbles are found in the Bunter; one kind he believes to have been 

 largely derived from the rocks in the north-west of Scotland ; the other set he states to be 

 more granular and altogether less compact in texture, resembling more the quartzites of 

 Budleigh-Salterton, the Lickey, and Hartshill ; to this rock, he states, belong, so far as 

 he has seen them, the pebbles collected by Mr. Perceval and Mr. Jennings. I must, 

 however, leave this matter for further consideration, and proceed without delay to the 

 description of the species of Brachiopoda that occur in the Budleigh-Salterton pebbles. 



Conclusion. — I have endeavoured, briefly and fairly, to express the views enter- 

 tained by geologists with respect to the four sources of derivation, and it seems to me that 

 the Channel hypothesis is the one that offers the greatest degree of probability, although 

 it is not possible to put the matter to the test. It has also been shown that rocks in 

 situ, agreeing with that of the pebbles, and with the same fossils, occur abundantly in 

 Normandy, Brittany, and the Department of the Manche ; also that no Devonian nor 

 Silurian Rocks in England have shown a similar assemblage of species as those that 

 occur in the pebbles, — that the pebbles of the age of the " Gres Armoricain " could not 

 have been derived from Silurian Rocks of that period in England, — and that only one or 

 two of the Caradoc species of Brachiopoda found in the pebbles could have been obtained 

 from Cornish quartzites. 



