Chap. XVI.] 
DEVONIAN OF THE EHlNE. 
395 
and the ' Systeme Rhenan ' of Dumont. This mass being on the whole very- 
schistose, and having a very pronounced transverse slaty cleavage, the true un- 
dulations of the beds can be recognized by practical geologists only ; still the 
distinction between cleavage and stratification is clearly to be seen. 
These rocks contain many remarkable fossils, among which may be noticed 
the large and broad-winged Spirifers Sp. hystericus and Sp. speciosus, Tere- 
bratula Archiaci, many species of Pterinea, some Orthides, especially O. cir- 
cularise Leptaena plicata, Chonetes semiradiata, Sow. (C. sarcinulata, Schloth. ?), 
Pleurodictyum problematicum, Phacops (Crypheeus) laciniatus, Ph. latifrons, 
and both smooth and spinose species of Homalonotus — H. Ahrendi and H. 
armatus, &c* 
According to all the Prussian geologists, the thin band of theWissenbach Slates, 
with its numerous small pyritized Orthoceratites and Goniatites, the chief of 
which are Orthoceras (Bactrites) gracile, and Goniatites compressus, overlies the 
Spirifer-sandstone. In admitting that the fauna of this slaty band is rather pe- 
culiar, MM. Sandberger affirm that it contains from eight to ten species like those 
of the Spirifer-sandstone ; among which areCtenodonta solenoides, Goldf., Pha- 
cops laciniatus, Rom., and P. brevicauda, Sandb. Thus, by means of their im- 
bedded organic remains, a natural union subsists between these two rocks, 
which in the Rhine country constitute the Lower Devonian f . 
This Lower Devonian mass — at least, all that portion of it which is charac- 
terized by broad- winged Spirifers — was long ago recognized X as extending 
largely over the Prussian Provinces on the left bank of the Rhine, which are 
watered by the Moselle, the Lieser, and the Ahr. Spreading over vast tracts 
east and west of Coblentz, it comprises the Systeme Coblentzien and Systeme 
Ahrien of Dumont; for the very same fossils pervade both these districts 
watered by the Rhine and the Ahr, and the distinction attempted to be drawn 
by the eminent Belgian geologist between these two so-named deposits was 
founded on mineral distinctions only. 
Middle Devonian of the Rhine ('Eifel Limestone' and ' Younger Rhenish Grau- 
wacke ' of Ferd. Romer ; ' Lenne-Schiefer ' of von Dechen). — The strata suc- 
ceeding to the Lower Devonian on the right bank of the Rhine, like the pre- 
vious beds, consist of schists and sandstones; but lenticular-shaped masses of 
limestone prevail at intervals. They there occupy a wide tract which is watered 
by the Agger, Vohne, and Lenne. The Lenne-schists of von Dechen, as laid 
down in the splendid new geological map of the Rhenish Provinces, occupy a 
broad tract of country, particularly on the right bank of the Rhine. After 
various undulations, and with many associated bosses of erupted igneous rocks, 
these strata, which are charged with much iron-ore, plunge on the right bank 
of the Rhine under the great band of limestone which, ranging by Elberfeldt 
and Schwelm to Iserlohn, and appearing also at Paffrath and Refrath near 
Cologne, is the well-known equivalent of the chief or upper band of the Eifel 
Limestone. A laborious examination of the country by M. Ferd. Romer led, 
however, to the separation of these strata from the lower division or the ' Spi- 
riferen-Sandstein,' and has shown that they are united with the Stringocephalus 
or Upper Eifel Limestone which covers them. It has, in short, been found that, 
whilst they contain few species in common with the underlying rocks, they are 
* The Homalonotus Hersehelii, ' Sil. Syst.,' a ser. 2. vol. vii. p. 204.) 
fossil formerly sent to me from the Cape of Good t In the Caub Slates, which are intercalated in 
Hope by Sir John Herschel, and all the spinose the sandstones of the lower division, the MM. 
forms of this genus, are now known to belong to Sandberger have found Phacops laciniatus, with 
Lower Devonian and not to Upper Silurian rocks. P. latifrons, Homalonotus planus, and some Or- 
(M. Sandberger in Neues Jahrb. 1852, p. 581 ; and thoceratites. 
Messrs. Sharpe and Salter in Trans. G-eol. Soc. J Trans. Geol. Soc. ser. 2. vol. vi. p. 280. 
