400 
SILTJKIA. 
[Chap. XVI. 
The group terminates upwards in a mass of olive and brown schists alter- 
nating with calcareous and dolomitic courses, the whole forming the usual 
borders of the coal-basins of Belgium. This, the highest Devonian group, is 
characterized by containing Orthis striatula, Schloth., Spirifer disjunctus, Sow. 
(Sp. Verneuilii, Murch.), Sp. comprimatus, Schloth., Strophomena Dutertrii, de 
Vern., Productus subaculeatus, Murch., Acervularia pentagona, Goldf., Favo- 
sites polymorphus, Goldf., &c. 
This is the upper member of the Petherwin group of English geologists, and 
is represented in North Devon by the sandy rocks of Barnstaple, Pilton, Croyde, 
Baggy Point, &c. It has been traced by de Koninck in Belgium, at Manche, 
Rhisme (Namur), Huy, Verviers, Chaufontaine, and Philippeville, and is well 
seen in the Boulonnais, where it is clearly distinguished from the lowest Car- 
boniferous rocks, by which it is conformably surmounted. 
Certain fossils of this age have as wide an extension as those of the under- 
lying divisions of the Devonian rocks, since they have been identified, by David- 
son, de Koninck, Salter, &c, from China * and other parts of Asia, and are 
abundant in Russia and Siberia. 
In terminating this sketch of the Devonian rocks of the Rhenish Pro- 
vinces and Belgium, it may be observed that, notwithstanding a certain 
similarity in general aspect of the fossils, even the lowest Devonian here 
indicated is entirely different in its fossil species from the Upper Silurian 
of any part of Europe ; whilst the Middle (or typical) Devonian is still 
more distinct. Neither of these rocks contains, for example, any Silurian 
species of Crustacean or Cephalopod ; the genera of the central masses are 
peculiar ; and Graptolites, which occur from the bottom to the top of the 
Silurian rocks, are unknown in any Devonian stratum. The Devonian and 
Upper Silurian are therefore infinitely more distinguished from each other, 
as natural-history groups, than the Lower and Upper Silurian, which, on 
the contrary, are linked together (as proved in the earlier Chapters) by a 
considerable number of the same species of Crustaceans, Cephalopod and 
Brachiopod Shells, Corals, and Graptolites. 
According to de Yerneuil, the Lower Devonian rocks of the Rhine are 
the equivalent of the Oriskany Sandstone of the United States, as will be 
explained in a subsequent Chapter. Other analogies have been indicated, 
by means of their fossils, between these Continental deposits and the Mar- 
cellus Slates and Hamilton Group of North America ; but, for the present, 
let us simply bear in mind that, whether we regard the physical order of 
the masses, or their imbedded remains, the Rhenish and Belgian rocks 
(which have afforded more than 450 species of fossil animals) are not 
only really remarkable counterparts to the succession in Devonshire, but, 
in consequence chiefly of the perseverance and activity of their explorers, 
have already much outnumbered in fossils their British equivalents. 
* The respected Chinese medical missionary, in the interior of that vast country, which are 
Mr. W. Lockhart, who communicated to the identical in specific character with Spirifer Ver- 
Itoyal Geographical Society a comprehensive neuilii, Sp. Archiaci, Productus subaculeatus, and 
memoir on the great watercourses and on the other European forms : coal also abounds in that 
productions of China, supplied me with Upper- region. 
Devonian fossils from the province of Tse-chuen, 
