ably into the Carboniferous series.

The Devonian rocks of Devonshire are likewise divisible into a
lower, middle, and upper division. The _Lower Devonian_ or _Lynton
Group_ consists of red and purple sandstones, with marine fossils,
corresponding to the "Spirifer Sandstein" of Germany, and to the
arenaceous deposits (Schoharie and Cauda-Galli Grits) at the base
of the American Devonian. The _Middle Devonian_ or _Ilfracombe
Group_ consists of sandstones and flags, with calcareous slates
and crystalline limestones, containing many corals. It corresponds
with the great "Eifel Limestone" of the Continent, and, in a
general way, with the Corniferous Limestone and Hamilton group
of North America. The _Upper Devonian_ or _Pilton Group_, lastly,
consists of sandstones and calcareous shales which correspond with
the "Clymenia Limestone" and "Cypridina Shales" of the Continent,
and with the Chemung and Portage groups of North America. It
seems quite possible, also, that the so-called "Carboniferous
Slates" of Ireland correspond with this group, and that the former
would be more properly regarded as forming the summit of the
Devonian than the base of the Carboniferous.

In no country in the world, probably, is there a finer or more
complete exposition of the strata intervening between the Silurian
and Carboniferous deposits than in the United States. The following
are the main subdivisions of the Devonian rocks in the State of
New York, where the series may be regarded as being typically
developed (fig. 67):--

(1) _Cauda-Galli Grit_ and _Schoharie Grit_.--Considering the
"Oriskany Sandstone" as the summit of the Upper Silurian, the
base of the Devonian is constituted by the arenaceous deposits
known by the above names, which rest quite conformably upon the
Silurian, and which represent the Lower Devonian of Devonshire. The
_Cauda-Galli Grit_ is so called from the abundance of a peculiar
spiral fossil (_Spirophyton cauda-Galli_), which is of common
occurrence in the Carboniferous rocks of Britain, and is supposed
to be the remains of a sea-weed.

(2) The _Corniferous_ or _Upper Helderberg Limestone_.--A series
of limestones usually charged with considerable quantities of
siliceous matter in the shape of hornstone or chert (Lat. _cornu_,
horn). The thickness of this group rarely exceeds 300 feet; but
it is replete with fossils, more especially with the remains
of corals. The Corniferous Limestone is the equivalent of the
co