549 
into the lower division of the ppc system (the Caradoc sand- 
sell 
. The last natural group (the (Shileketon system). For all details 
coaleanes this system the author refers to the abstracts of Mr. Mur- 
chison’s papers, and to his published works. 
The author then describes a series of sections :— 
(1.) East of the Berwyns, in which the Caradoc sandstone is 
finely developed; containing the Llandeilo flagstone and other cha- 
racteristic calcareous and shelly bands. 
(2.) The sections north of the Berwyns, connecting Montgo- 
meryshire with Denbighshire. The ascending series derived from 
these sections is described as follows :— 
(1.) A series of beds several thousand feet in thickness, and’at 
the north end of the Berwyns apparently forming a passage 
between the Upper Cambrian and lowest portion of the Silurian 
system. 
(2.) Bands of calcareous slate with numerous organic remains of 
the ‘‘ Caradoc sandstone,’ surmounted by roofing slate. 
(8.) Series of flagstones, more or less calcareous, with many Or- 
thoceratites and two species of Cardiola, &c.; overlaid by, and 
associated with, irregular masses of roofing slate with a trans- 
verse cleavage. 
(4.) Flagstones and rotten slates, many parts m an imperfect state 
of induration, and the whole surmeunted by the carboniferous 
limestone.—Of the preceding section the lower part of No. 3 
is identical with the series of Long Mountain in the Silurian 
sections of Mr. Murchison; but No. 4 is mineralegically un- 
like anything he has described, although it has been found by 
Mr. Bowman to contain, in its highest portion, some of the 
fossils of the Upper Ludiow rock. It appears from these details 
that the Silurian system, although its subdivisions are obscure 
from the absence of the Wenlock and Ludlow limestones, is 
very fully developed in North Wales. 
An examination of the few Snowdonian fossils of the author gives 
the following results :— 
(1.) Impressions of corals (Turbinolopsis ?) (Cwm Idwal and Moel 
Hebog). 
(2.) Stems of Encrinites (Cwm Idwal). 
(3.) Orthis pecten, O. Actonia, O. flabellulum, O. canalis ( Snow- 
don and Moel Hebog). 
He has many fossils from different parts of the Berwyn chain; 
and he believes them (as stated in a former abstract) to be nearly 
all known Silurian species, but they have not yet been carefully 
examined. He possesses also a good series of fossils from the eastern 
side of the Berwyns, and from portions of the more northern sec- 
tions; but as the whole series is unequivocally Silurian (extending 
from the Llandeilo flagstone to the Upper Ludlow rocks), he has 
not thought it at present necessary to trouble the Society with any 
enumeration of species. 
From a review of these facts he concludes, that in the great-sec- 
