Silurian and Devonian Systems. 167 



The Calcaire de Lievin has yielded six species, with Dayia 

 navicula in great abundance. 



The Calcaire d'Angres is a blue limestone, crinoidal at the base, 

 with thirty-two species, including RhyncJionella nucula (large form 

 identical with the characteristic form found in our Rhynchonella 

 Beds), Acaste Downingice, Calymene Blunienhachii, and Leptcena 

 rhomboid alis. 



The Grauwacke de Drocourt has yielded sixty-three species, 

 including Sjnrifera elevata, Orthis lunata, 0. canaliculata, 

 Homalonotus spp., Pterinaa retroflexa, and numerous Orthoceratids, 

 including the " nodules a Orthoceras ", so well seen in the 

 Rhynchonella and Chonetes Beds of Shropshire/ 



The Arkose de Bois-Bernard is a local bed of coarse sandstone 

 at the base of the Schistes de Mericourt. 



The Schistes a Tentaculites de Mericourt yield a very rich fauna of 

 fifty-eight species, including Retzia Bouchardi, Tentaculites irregularis, 

 Pterincea retroflexa, and other lamellibranchs, Cryphceus spp., 

 abundant Primitia Jonesi, Orthis personata. There can be no doubt 

 of the identity of this bed with the Schistes de Mondrepuits. 



The Psammites de Lievin have alternating beds with Pteraspis 

 Gosseleti (Leriche), Cyathaspis Barroisi (Leriche), and typical marine 

 beds with Modiolopsis cofnplanata and Orhicidoidea. 



The Schistes et gres de Pernes and the Schistes et gres de Vimy 

 are only separable by their faunas, the former being characterized 

 by Pteraspis Crouchii, Pt. rostrata, and Cephalaspis Lyelli ; the 

 latter by a rich and entirely different series of fish remains not 

 yet described. 



C. Shropshiee. 



It is not necessary to repeat here the well-known established 

 sequence in Shropshire.^ 



The beds, which I have termed in the western area the 

 Platyschisma shales, represent a deeper-water facies of the lower 

 part of the Downton Castle Sandstone. The fossils mentioned on 

 p. 233 of my paper as being survivals from the Chonetes Beds are 

 perhaps more correctly regarded as the continuation of the normal 

 fauna, whereas the fauna associated with Platyschisma helicttes 

 is a specialized shallow-water one. This point needs further 

 investigation. 



II. NOTE ON THE CORRELATION TABLE (p. 169). 



This is practically identical with that already advocated by 

 Barrois, Pruvost, and Dubois (op. cit.), who approached the subject 

 from an entirely different standpoint — that of the study of the faunas 

 in the North of France. My conclusion as to the relation of the 



1 Stamp, loc. cit., pp. 228-9. 



2 Elles & Slater, Quart. Journ. Geol. Soc, vol. Ixii, 1906, p. 195 ; Stamp, 

 ibid., vol. lx>:iv, 1918, p. 221, 1919. 



