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list of fossils is subjoined, and the authors regard the numerous Go- 
niatites as rather connecting the group with the overlying Devonian 
rocks; while the trilobites and orthoceratites, &c., some of which 
cannot perhaps be distinguished from known Silurian fossils, seem 
to link it to the Silurian system. 
Below the preceding comes a group of vast thickness, composed 
of earthy schistose beds, passing on one hand into shale, on the other 
into coarse slate, and alternating indefinitely with bands of psammite, 
sometimes passing into coarse arenaceous flagstone, sometimes into 
thick beds of sandstone. Nearly throughout are occasional obscure 
vegetable impressions, and in the upper part are courses of lime- 
stone and caleareous bands, with innumerable impressions of fossils. 
In the lower part, the limestone bands seem gradually to disappear, 
and the whole passes into a formation of graywacke and graywacke 
slate, in some rare instances producing a good roofing-slate. For many 
miles south of the undisturbed range of the lower Westphalia lime- 
stone, the prevailing dip is about north-north-west. The country 
round Siegen is regarded as a kind of dome of elevation, composed 
of the lower part of this series; for still further south the dip is re- 
versed to the south-south-east ; and in a traverse from Siegen to the 
Taunus, across the strike (a distance of about fifty miles), the same 
dip is continued, with very few interruptions. Considering their 
high inclination, this fact seems to give an almost incredible thick- 
ness to the deposits in question. But the vertical sections do not 
give the order of superposition ; for at Dillenburg, and on the Lahn, 
two great Devonian troughs are brought in among the older strata, 
without any general change of dip; and if we accepted the vertical 
sections as the sole proofs of superposition, we must place the Devon- 
ian and a part of the carboniferous series under the chain of the 
Taunus. The authors therefore endeavoured to apply the method of 
Professor Dumont, and found their results confirmed by the sections 
of the lower Lahn. 
Many other local details are given, and the authors having deter- 
mined the geometrical position of the great mineral masses, next at- 
tempt to define their age from their fossils. In the arenaceous and 
calcareous group under the lower Westphalia limestone, many spe- 
cies of the genus Pterinea (Goldfuss), Homalonotus, Orthis, &c. &c., 
begin to prevail. Along with these are forms at present unknown 
in England, e. g. Hysterolites of Schlotheim, and two species of Del- 
thyris,—D. macroptera and D. microptera (Goldfuss). The same 
groups of fossils are found on the banks of the Rhine; and in a 
quarry near Unkel are many fossils of the genus Orthis, among 
which were O. pecten, O. flabellula, O. rugosa. Along with them 
was Terebratula Stricklandii, and the group was considered charac- 
teristic of the lower Silurian rocks of England. 
On a review of the whole evidence, the authors place this vast 
succession of strata in the Silurian system, without professing to 
separate the several parts into distinct groups, on a parallel with the 
several groups of the Silurian system of England. This is forbid- 
den by the absence of distinct calcareous bands, and also by the 
