338 Thos. Davidson—Brachiopoda of Brittany and S. Devon. 
Devon, and the Hangman grits in particular, and arrived at the 
conclusion that the Devonian “pebbles” accumulated at Budleigh 
Salterton could not have been derived from North Devon, and 
especially from the Hangman grits, which contain very few Brachio- 
poda besides Stringocephalus Burtini, a species that has not hitherto 
been found in any of the “pebbles” above alluded to. 
In 1864, Messrs. Vicary and Salter attributed the Budleigh 
Salterton “pebbles” to the Silurian period. In 1869 I showed that 
while a portion of the pebbles were unquestionably Silurian, another 
portion were undoubtedly Devonian. 
Since then, M. Gaston de Tromelin and M. Lebesconte’ have 
shown by their elaborate study of the Silurian and Devonian rocks 
of Normandy and Brittany that the Lower Silurian pebbles of 
Budleigh Salterton were distinctly referable to two well-defined 
stages or horizons. First to the “ Grés Armoricain,” which, according 
to M. de Tromelin, would correspond with our Lowest Llandeilo, 
or perhaps, even “Stiper Stones,” and which in Brittany, as well 
as at Budleigh Salterton, would be characterized by the presence of 
Lingula Lesueuri, L. Hawkei, L. Salteri and Dinobolus Brimonti— 
species that have not hitherto been discovered in any rock, im situ, in 
Great Britain. 
Above the Grés Armoricain, in Brittany, we find slaty schists 
with an occasional band of yellow sandstone, in which Brachiopoda 
are abundant; but, with the exception of Orthis Budleighensis, which 
abounds at Andouville and La Hunandiere, I could find among the 
numerous specimens kindly lent me by M. Lebesconte no other 
species with which ] was acquainted that occurred likewise in the 
Budleigh Salterton pebbles. 
We must, however, not omit to observe that at La Couyeére 
in Brittany, according to M. M. Rouault. M. de Tromelin, and 
M. Lebesconte, black slates occur full of flattened distorted speci- 
mens of a large Orthis, the type of Rouault’s Orthis Berthosi. 
Thanks to M. Lebesconte I have been able to examine a number 
of specimens of this flattened species. It is marginally nearly 
circular, measuring some 19 or 20 lines in length and breadth, the 
surface of the valves covered with numerous fine radiating raised 
lines or riblets, crossed at intervals by concentric lines of growth. 
The typical form of Rouault’s species has not, that I am aware of, 
been hitherto discovered in Great Britain. 
Above the schists we find the sandstones and quartzites of 
May, St. Germain-sur-Ille, La Bouexiére, and other places, so 
well described by the French geologists above named. This 
«Grés de May” has long been considered to be referable to the 
Caradoc, and in it are found immense numbers of internal casts and 
impressions of Orthis Budleighensis, as well as of a small variety of 
Orthis Berthosi, to which I gave the varietal designation of erratica, 
1 Assoc. Franc. pour |’avancement de la Science, Congrés de Nantes, 1875, Bull. 
Soc. Linn de Normandie, 3 ser. vol. i. p. 5, 1877; Congrés du Havre, 1877, Bull. 
Soc: Geol. de France, 3 ser. t. iv. p. 588, 1876; and M. J. Moriere, Note sur la 
grés de Bagnoles, Bull. Soc, Linn. de Normandie, 8 ser. vol. ii. 1868. 
