332 BRACHIOPODA OF THE 



No other species of Brachiopoda besides Lingula Salteri and indeterminable fragments 

 of internal casts of Orthis and Athgris ? have been noticed from the " Gres Armoricain." 

 This sandstone or quartzite entirely agrees in mineral composition, aspect, colour, and 

 fossil contents, with certain pebbles (see p. 323) of Budleigh-Salterton ; and if specimens 

 were mixed np together they could not be distinguished. As far as I am aware, 

 "Armoricain" rocks of that epoch, with their characteristic fossil remains, do not 

 occur in situ in Great Britain ; so that the Budleigh-Salterton pebbles of that age must 

 have been drifted from rocks, in situ, somewhere out of England, and the French localities 

 are the only ones where we at present know quartzite rocks of that age to occur. 



2nd. Higher up in the series of Lower-Silurian rocks, in Erance, we come upon 

 thick beds of sandstones and quartzites of Caradoc age. These are largely developed 

 in Normandy, in the Department of the Manche, in Brittany and elsewhere ; and, as 

 already stated, these are best known in Erance by the name of the " Fiage du Gres de 

 May." In Normandy, these rocks were first noticed by M. Herault in the ' Annales des 

 Mines ' for the year 1824, also by M. de Caumont, 1 Prof. Deslongchamps, 2 and 

 especially by M. de Tromelin in 1877. 



The rock or quartzite composing the " Gres de May '' varies considerably in com- 

 position and colour in different localities. At May, in Normandy, it is a hard, compact, 

 reddish quartzite, extensively quarried for excellent road-material, but at Jurques, 

 Campandre, Mount Robert, and other places in Normandy, it is either white, light-grey, 

 or yellow. The grey kind of Jurques also very nearly resembles the light-grey quartzite 

 met with, in situ, in South Cornwall; and certain pebbles of similar rock at Budleigh- 

 Salterton present all the variations in mineral composition, from soft sandstone to 

 compact hard quartzites, which we find in Normandy. The prevailing Brachiopod at 

 May is 0. Budleighensis ; and so likewise in these particular pebbles at Budleigh- 

 Salterton. At May, M. de Tromelin found likewise, but very rarely, Orthis Berthosi, 

 var. erratica, and Lingula Morierei, species that occur likewise in these Budleigh- 

 Salterton pebbles. The same sandstone, with 0. Budleighensis, was also found by Mr. 

 Bonissent in various places in the Department of the Manche. 



From any of the places above named, the Budleigh-Salterton pebbles of that age 

 might have been derived, so similar are the rocks and fossils that occur in both 

 localities ; but it is more probable, and indeed I might say certain, that the rock 

 furnishing the pebbles of the age of the " Gres de May " occurred much nearer to our 

 island. 



In Brittany the rocks belonging to the period of the Gres de May differ somewhat 

 from those of Normandy. For instance, at St. Germain-sur-l'Ille (Ule-et-Vilaine) the 



1 " Me'moires Geologiques sur quelques terrains de la Normandie occidentale" ('Mem. de la Soc. 

 Linneenne du Calvados,' 1825); also "Essai sur la Topographie geognostique du Department du 

 Calvados," 1828. 



2 " Me moire sur les corps organises fossiles du gres intermediane du Calvados " (' Mem. de la Soc. 

 Linn, du Calvados,' 1828). 



