74 
SILUEIA. 
[Chap. IV. 
underlying the conglomerates at the base of the Llandovery series, are full of 
characteristic Caradoc fossils. Thus, in Cilgwyn Park, under the conglomerate 
terrace of Glan Towy, the beds, which are quarried in the demesne, consist of 
dark-grey, earthy slates, and contain the following characteristic fossils, — iden- 
tical with those forms which are met with everywhere upon the banks of the 
Onny, or at Bala : — 
Trinucleus seticornis ; Asaphus Powisii ; Hlaenus Bowmanni, with species of 
Calymene and Cybele ; Orthis spiriferoides, M'Coy; 0. biforatus; O. insularis; 
Ctenodonta ; a Diseina ? (Patella Saturni of Portlock) , a species known at 
Cheney Longville, and in the Caradoc schists of Tyrone, Ireland ; Bellerophon 
bilobatus ; B. nodosus ; Theca triangularis, Portl. ; Sphaeronites balthicus ; and a 
fine species of Pleurocystites, with some of the ordinary Corals. 
The same Caradoc beds also range round under Blaen-y-cwm, South of Llan- 
dovery. They there contain similar fossils, with the addition of Lichas laxatus, 
M'Coy, Orthis porcata, id., and Orthoceras ibex, Sil. Syst., now known to range 
from the Caradoc to the uppermost Ludlow rocks. Further north, between 
Rhayader and Builth, the Caradoc strata everywhere appear beneath the Llan- 
dovery rocks; and at Troed-y-Rhiw the same fossils are obtained, including 
a peculiar Crinoid, the Pleurocystites, together with the Bellerophons and the 
Orthoceras vagans so common at Bala. 
Thus we have in that tract an unbroken ascending series from the 
Llandeilo Flags through the Caradoc into those beds with Pentameri which 
I formerly grouped with the latter formation, and which are, indeed, 
essentially connected with it. 
In Pembrokeshire also, at Llampeter Felfry and Llandewi Felfry, the 
Llandeilo Flags, constituting the thickest limestones known in the Silurian 
rocks of Wales, occur, as already stated, in low undulations, dipping under 
strata which also stand in the place of the Caradoc. (See diagram, p. 54.) 
A thin and impure calcareous course, exposed at Sholeshook, near 
Haverfordwest, and which was formerly classed with the Llandeilo 
Flags*, is also clearly separated from that deposit, both by superposi- 
tion and characteristic organic remains. Besides Brachiopods, Trilo- 
bites, and numerous Corals common in the beds at Bala, there are also 
found in it Encrinite-like forms with slender stems and grape-shaped 
heads, the Sphaeronites of old authors (Cystideae of Yon Buch). Some of 
these will be figured and described in another chapter, — Echinosphaerites 
aurantium and E. balthicus, both common Russian and Scandinavian species, 
being among the number. 
In the vast tracts of Carmarthen, Cardigan, Radnor, and Montgomery, 
to the west of the original Silurian region* which have been examined by 
the Geologists of the Survey, and illustrated in their large coloured sections, 
it is known that few or no rocks older than the Caradoc (or Bala) forma- 
tion, or younger than the Lower Llandovery rocks of the next chapter, 
ever appear — even up to the sea-cliffs extending from Cardigan to Aberyst- 
with and Machynlleth (see colour 2 C of Map) ; so much do the same 
bands of sandstone and schists (usually affected by a transverse cleavage) 
* Sil. Sysfc. p. 387. 
