330 BRACHIOPODA OF THE 



that Prof. M'Coy identified some specimens of 0. Budleigliensis with Orthis retrorsistria , 

 to which, however, they do not belong, although some small flat dorsal valves from the 

 Middle Bala Slates of Cerigdrudion and other places, in the Woodwardian Museum, very 

 closely resemble similarly flattened valves of Orthis Budleigliensis that occur in the light- 

 grey quartzite of Cornwall. 0. Budleigliensis never, however, attains the dimensions of 

 full-grown 0. retrorsistria. If, therefore, my identifications are correct (and for these I 

 have given figures), the light-grey quartzite of Cornwall would represent the " Gres de 

 May " of Normandy with its characteristic Orthis Budleigliensis. It will also be remarked 

 that all the Brachiopoda found in the Lower-Silurian Rocks of Cornwall are of Bala or 

 Caradoc age, and that we have not yet discovered in Cornwall beds of quartzite repre- 

 senting the " Gres Armoricain," nor any of its characteristic species, such as Lingula 

 Lesueuri, L. Hawkei, L. Salteri, and Dinobohis Brimonti, which are all found at 

 Budleigh-Salterton in the quartzite pebbles. 



Only two species of the " etage du Gres de May " that occur in Cornwall, Orthis 

 Budleigliensis and Orthis Berthosi, var., are found in pebbles at Budleigh-Salterton ; 

 therefore, even if some of the pebbles in the last-named 'locality were derived from 

 Cornwall, we would have to seek out of Great Britain for rocks, in situ, whence all the 

 other species must have been derived. 



I am ready to admit, with Messrs. Peach and Etheridge, that some pebbles found at 

 Budleigh-Salterton are similar to the quartzites of Cornwall, and contain one or two of the 

 same species ; but it seems strange that, if the quartzite pebbles came from there, we do 

 not find along with them pebbles of the dark-grey or greenish ferruginous rock which in 

 Cornwall contains Orthis calligramma, 0. scotica, and Strophomena grandis. 



At one time Mr. W. Linford was in favour of a southern derivation of the Budleigh 

 pebbles, but he now seems very doubtful that such was the case, and thinks a south- 

 west derivation more probable. It has also been suggested that the red quartzites of 

 May, in Normandy, could not be the same as the grey quartzites of Cornwall, but even 

 in Normandy the quartzites of the " Gres de May" vary in colour at St. Germain-sur- 

 Ille, Jurques, Campandre, Mont Robert, &c, some being reddish, others grey, yellowish, 

 or even nearly white. M. de Tromelin seems to think, likewise, that it is not from 

 Cornwall that the Lower-Silurian pebbles were derived, but considers them of French 

 origin. 



It will also have to be ascertained if any portion of Cornwall was submerged in as 

 early Triassic times as those during which the pebble-bed was deposited ; but these and 

 allied geological questions I must leave for other investigations. I have simply dealt with 

 what appeared to me to be the facts of the case, as far as I have been able to make them 

 out, and the volumes of the Palaeontographical Society ought not to be occupied with 

 lengthened discussions on geological questions. I have, however, felt obliged to enter 

 briefly upon certain considerations, as they are connected with the age of the pebbles and 

 the species of fossils they contain. 



