*02 Geological Society. 



through large tracts of Westphalia the two could not, by a series of 

 land specimens, be distinguished from one another. The fossils of 

 this limestone are verj' abundant, and several sections are given in 

 detail, to show their local distribution. Among the most character- 

 istic and abundant in these sections the following are enumerated : 

 Stromatopora polymorpha, S. concentrica, Favosites ramosa, Favo- 

 sites polytnorpha, F. spongites, F. Gothlandica, Strygocephalus Bur- 

 tini, Gypidium, Terebratida aspera, Turritella coronata, T. bilineata 

 (Schlotheim), Biiccinum spinosum (Sowerbj^), &c. &c. From all 

 these facts, it is inferred, that this lower limestone of Westphalia is a 

 true Devonian limestone, exactly or very nearly on a parallel with 

 the great limestone of Soutii Devon. 



Local and detailed lists are added, and detailed sections are given, 

 connecting the whole series both with the upper and lower forma- 

 tions, especially one from the Possidonia schists and black limestones, 

 near Schelke, through the Devonian limestone, and to the lower 

 formations exposed on the banks of the Lenne, towards Altena. In 

 this section there is no ambiguity, and the defective evidence in the 

 sections of Devonshire, when we endeavour to connect the culm- 

 measures with the South Devon limestone, is here amply supplied. 



The authors then describe in detail the sections at Paffrath, near 

 Bensberg, on the right bank of the Rhine, near Cologne, where the 

 same Devonian limestone occurs, with a magnificent series of fossils ; 

 its position is, however, reversed, as it seems to dip under the lime- 

 stone near Bensberg, which is referred to the upper part of the Si- 

 lurian system. 



To the same geological epoch the authors also refer the compli- 

 cated metalliferous deposit of Dillenburgh, and the limestones of the 

 Lahn in the country of Nassau. At the former place the great con- 

 tortions and the extraordinary intrusions of trappean rocks make the 

 relations difficult ; but, considered on a great scale, the vast fossil- 

 iferous and calcareous group reposes on rocks considered of the Si- 

 lurian age: it contains a true Devonian group of fossils, and its 

 upper portion at Herbon is sui'mounted by a Possidonia schist, per- 

 fectly identical with that of Westphalia. The limestones of the 

 Lahn at Dietz, Weolburg, W^etzlar, &c., are still more unequivocally 

 Devonian ; and though the alternating masses of limestone and schist 

 are of enormous thickness (rivalling in that respect the whole series 

 of limestones and slates in South Devon), and the sections often 

 obscure, yet in descending the Lahn from Dietz to Nassau and Bad 

 Ems, they had a proof that the calcareous system is underlaid by 

 Silurian rocks. The appearance of these Devonian deposits near 

 the eastern limit of the old rocks, on the right bank of the Rhine, is 

 accounted for by enormous undulations, which have repeated over 

 again, in three or four great parallel troughs, the formations which 

 appear in their true place in Westphalia, on the northern limit of the 

 same ancient formations. 



§ 4. Silurian System. — The authors next describe the great se- 

 ries of rocks which rise from beneath the lower Westphalia lime- 

 stone, and state that in the long range from Elberfeldt to Iserlohn 



