72: PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [ Dee. 8, 
from the same, has there ever been a case observed where rocks con- 
taining Devonian fossils overlie Silurian ones with Silurian fossils, the 
matrix being the same in both cases*? The question is difficult to 
answer; but when we examine the contents of these “ pebbles” (or 
“‘nopples,” as they are locally designated), it is not easy to suppose 
them of the same age, if our identification of the fossils is correct, 
because, so far as I know, in no locality hitherto investigated has 
such an assemblage been exhibited; but I would again remark that 
were we not positively assured by Messrs. Rouault, Salter, and De 
Verneuil that three or four of the Brachiopoda are in reality Lower- 
Silurian fossils, it would not be very difficult, I think, to refer most 
of them, if not all, to a single period. None of the rocks known in 
England have, however, presented a similar fauna; nor have the 
red sandstone and quartzite beds of May and Fengrolles in Nor- 
mandy, any more than those described by M. Rouault in Brittany, 
furnished more than a very small proportion of the species found in 
the Budleigh pebbles. Mr. Vicary seems, however, to believe that 
they may have been derived from a nearer source, and that they 
once formed a beach in the New Red Sandstone sea, similar to that 
of the Chesil bank near Portland; but we have no evidence of this 
that I can collect in the Channel; and even if such a bed did exist, 
it would not clear away the difficulty connected with the presence 
of fossils of two distinct periods (?). It has been suggested that a 
great similarity exists between the Budleigh fossils and those de- 
scribed by Messrs. Ribeiro and Sharpe from the Serra de Bussaco, 
in Portugaly; but I could not identify with certainty a single species 
of Brachiopoda as common to the Portuguese locality and that of Bud- 
leigh Salterton. It is true that those authors state that the lowest 
division of the Silurian system in Portugal is composed of quartzites, 
micaceous sandstones, &c.; but I can hardly suppose that any of the 
Budleigh boulders were drifted from that locality. A mystery still 
hangs over the derivation of these boulders, nor can I account for 
_ the supposed and extraordinary mixture of Silurian and Devonian 
forms in the same locality ; but I must place a reserve on the above 
statement, and qualify my meaning—namely, that although in this 
“remanié” deposit there appears to exist an assemblage of species 
peculiar to two distinct epochs, this mélange does not seem to occur 
in the same pebble; on the contrary, every individual boulder 
contains specimens referable either to the one or to the other epoch ; 
so that no mélange has been hitherto detected in the same pebble, or 
existed in the parent rock. It is to my mind quite certain (and I 
am supported in this opinion by M. de Verneuil) that those boulders 
which contain Spirifera Verneuilu, Rhynchonella naurita, Strepto- 
rhynchus crenistria, Productus Vicaryt, Chonetes, &c. are of Devonian 
age; consequently all other forms that occur in the same mass of 
rock along with these must necessarily belong to the same period. 
* We all know that conglomerates containing fragments of rock of different 
ages have been met with in several places. It is the matrix being the same 
that causes the difficulty. 
tT Quart. Journ. Geol. Soc. vol. xx. p. 135, 1853. 
