DESCRIPTIVE REMARKS. XXXili 
this formation is well shown. This intermediate group of strata, con- 
necting the Lower and Upper Silurian, was formerly called Upper 
Caradoc; it is now divided into a lower and an upper series—the lower 
and larger portion of the formation being related by its fossils to those 
of the Lower Silurian; the higher series, although containing some 
Lower Silurian species, is more evidently connected with the Upper 
Silurian. 
At the hills of Noeth Griig and Cefn-y-garreg, north-east of Llan- 
dovery, the whole formation is admirably exposed ; it is remarkable as 
being the only tract in England and Wales where the lower and upper 
portions have hitherto been observed in a continuous series; showing 
clear relations to the Caradoc beneath and the overlying Wenlock and 
other Upper Silurian strata. 
In Radnorshire, Shropshire, Herefordshire, the Malverns, &c., only 
the upper portion of the Llandovery series is present, forming, as Sir 
R. Murchison informs us, the natural base of the Upper Silurian 
rocks. 
About nine miles south of the Malvern range the Upper Llandovery 
or May Hill sandstone of Professor Sedgwick reappears, upon which 
the Wenlock and other Upper Silurian rocks are superimposed. At 
Tortworth also, in Gloucestershire, still more to the south, the Upper 
Llandovery sandstone, with much trap rock, occupies a large area, and 
is surmounted by the Wenlock formation, with two courses of lime- 
stone, and feeble representatives of the Ludlow rock. Siluria, 4th ed., 
. 100, 
The most eastern tracts in England where the Upper Llandovery 
rock appears are the Lower Lickey Hills, in Worcestershire, and near 
Barr, in Staffordshire, at both which places that rock supports the base 
of the Upper Silurian deposits of the adjacent tracts of Dudley and 
Walsall (2b7d.). 
In Scotland, on the banks of Girvan Water, Ayrshire, besides Cara- 
doc, and perhaps Llandeilo strata, there are in certain beds of fine 
micaceous dark grey sandstones an abundance of fossils of Llandovery 
type; and also, as in England and Wales, rocks in which typical Upper 
and Lower Silurian fossils are mingled together ; these Silurian deposits 
of Ayrshire are covered towards the north by the Old Red and Carboni- 
ferous formations. 
In the west of Ireland, in Connemara and the adjacent tracts, near 
Cong, in the Co. Galway, and extending to Uggool, in Mayo, equiva- 
lents of the Llandovery rocks, consisting of conglomerate, sandstone, and 
schists, occur in patches, containing in some places a profusion of fossils, 
the strata resembling both in its lithological and paleontological cha- 
racter some of the upper fossiliferous beds described as occurring on the 
banks of the Girvan Water in Ayrshire. 
The organic remains from these rocks, though exhibiting on the 
whole a peculiar facies, and containing some distinctive species, show 
an evident continuity and passage from beds in which Lower Silurian 
typical forms prevail, into others, at its higher portion, where Upper 
e 
