MOltRIS — BKlTfsH KOS.-U I.S. 
23n 
especially those which avouLI be suited to live in a pamly bottom. 
Ammonites and Eolemnitcs are in nnnsiiul numbers, and many of them 
of great size. It is also distinguished ])y some very large Pectcns, and a 
fine Gryphfca {G. gigantea), a species of Pinna, and by univalves equally 
gigantic. Most of the fossils exist in the form of casts : and the ancient 
genera, Splrifer, Lcptasna, Orbicula, and Lingula, so abundant in the 
older formations, still linger hero. Hcmains of Pentacrinites, one of the 
most curious and beautiful of the Crinoidea, vertebra of Ichthyosauri, 
with the solitary humerus of a Pterodactyle, have also been noticed. 
The stone is hard, and the fossils difficult to extract in consequence ; 
yet, from their abundance and variety, the collector is sure to secure 
a characteristic and instructive series. The most prolific localities 
in Gloucestershire are the quarries at Brcdon, Alderton, Dumbleton, 
Gretton, Churchdown, and Hewlett's Hill, close to Cheltenham. 
{To le contimted.) 
BRITISH FOSSILS, STE.iTIGIlAPHICALLY APtRAXGED. 
By John IToeris, F.G.S. 
I. r A L yE O Z O I C SYSTEM. 
(C'0!i(i/i»';.:Z ji-oin page 194.) 
C. LLA\DOVEKY ROCKS, OR MIDDLE SILI UIAN. 
Wales, SnROPsiiiRF, 
&c. 
Uppei- Llandovei-y j 
M.ay Hill Sandstone' 
Lower LUmdovery 
Plynlynion vocks. , 
CuMnURI.ANI). 
ILu'd slliocous 
sandstones or Ton- 
iston grits. 
Scotland. 
Shelly sandstones 
and shales of Saugh 
Hill, and Mulloch 
Hill, Ayrshire. 
Irelasd. 
Conglomorates, 
sandstones, and 
schists, near Maani, 
&c. Galway, Uggool, 
Mavo. 
The Llandovery rocks were so named by Sir 11. Murchison from the 
locality in South Wales whure they are most fully developed, and 
where their physical relations to the for.mntions above and below them 
are clearly exposed. These rocks constitute an intermediate place in 
the Silurian table, connecting, by some of their contained organic 
remains, the fauna of the upper and lower Silurian groups. The 
upper Llandovery rock contains many shells common to the Wcniock 
beds, and is considered to form the natural base of those deposits; on 
the other hand, the lower Llandovery is related by its fossils to the 
Caradoc beds below, and both members of this formation are united by 
having certain fossils in common and peculiar to them, but are chiefly 
characterized by the abundance of some species of Petraia, Atrypa, 
V 
