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sand Silurian systems. Subsequent examination has proved 
: such is the case; but this distinction could not have been ascer- 
aned had not Mr. Murchison published his work on the Silurian 
system. 
In the order of sequence there is now no difference of opinion 
between the authors and Mr. De la Beche and Mr. Williams, the 
only point on which the agreement is not common, being the class 
to which the formations should be assigned. 
The authors then explained that their sections both in S. Devon 
and N. Cornwall indicate, with some limited exceptions, a passage 
downwards, the transition being stratigraphically true, whether the 
beds be examined along the banks of the Taw, near Barnstaple, on 
the north, or to the west of Launceston, on the south of the great 
trough. 
The authors next gave an approximate list of the fossils, collected 
by themselves or placed at their disposal by the Rev. R. Hennah, 
_ Major Harding, and the Rey. D. Williams, referrmg them to the 
great mineral groups to which they belong, both in North and 
South Devon. 
Descending order in North Devon.—The shells in the uppermost 
group, beneath the culm, as at Barnstaple, in the North of Devon, 
and South Petherwin, near Launceston in the south, approach ge- 
nerally forms of the carboniferous system, consisting of Goniatites 
of new species, and of spined Producti and Spirifers, entirely unlike 
the species found in the Silurian system, but resembling those ob- 
tained in the mountain limestone. The same group contains also 
new species of Trilobites and Crinoidea. 
In the next underlying formation in the north, er the sandstone 
group, ranging from Baggy Point by Marwood and Sloly, occur new 
species of Cucullea, Avicula ? Cypricardia, and Orthocera ; one cast 
also has been obtained, undistinguishable from Bellerophon globatus 
of the Silurian system. In the same series are found casts of plants 
of considerable size, but in Professor Henslow’s opinion, quite 
distinct from any known coal measures remains. 
In the third descending group, but few fossils have yet been 
found, yet it has been ascertained to contain one of the varieties of 
Producta common in the overlying groups, and similar to the spi- 
nous species of the mountain limestone ; also a coral (Favosites po- 
lymorpha,) previously found in England only in the Upper Silurian 
rocks. 
The next descending series of beds, or the arenaceous deposits of 
Linton, contains few fossils, except towards its lower part, where 
calcareous matter re-appears, and in that portion a Spirifer has been 
obtained resembling the S. attenuatus of the mountain limestone, 
and a new species of Orthis, a genus characteristic of the Silurian 
system. 
In the Quantocks, which the authors consider as formed of the 
oldest strata in North Devon, organic remains appear to be rare, the 
principal hitherto procured consisting of Favosites polymorpha. 
South Devon.—Having thus shown that in North Devon there is 
