couleni_ (fig. 122, c), may attain a length of from one to
three quarters of an inch. The old group of the _Phyllopods_
is is likewise still represented in some abundance, partly by
tailed forms of a shrimp-like appearance, such as _Dithyrocaris_
(fig. 122, d), and partly by the curious striated _Estherioe_
and their allies, which present a curious resemblance to the
true Bivalve Molluscs (fig. 122, b). Lastly, we meet for the
first time in the Carboniferous rocks with the remains of the
highest of all the groups of _Crustaceans_--namely, the so-called
"Decapods," in which there are five pairs of walking-limbs, and
the hinder end of the body ("abdomen") is composed of separate
rings, whilst the anterior end is covered by a head-shield or
"carapace." All the Carboniferous Decapods hitherto discovered
resemble the existing Lobsters, Prawns, and Shrimps (the _Macrura_),
in having a long and well-developed abdomen terminated by an
expanded tail-fin. The _Paloeocaris typus_ (fig. 122, e) and the
_Anthrapaloemon gracilis_ (fig. 122, f), from the Coal-measures
of Illinois, are two of the best understood and most perfectly
preserved of the few known representatives of the "Long-tailed"
Decapods in the Carboniferous series. The group of the Crabs
or "Short-tailed" Decapods (_Brachyura_), in which the abdomen
is short, not terminated by a tail-fin, and tucked away out of
sight beneath the body, is at present not known to be represented
at all in the Carboniferous deposits.

[Illustration: Fig. 123.--_Cyclophthalmus senior_. A fossil Scorpion
from the Coal-measures of Bohemia.]

[Illustration: Fig. 124.--_Xylobius Sigillarioe_, a Carboniferous
Myriapod. a, A specimen, of the natural size; b, Anterior
portion of the same, enlarged; c, Posterior portion, enlarged.
From the Coal-measures of Nova Scotia. (After Dawson.)]

[Illustration: Fig. 125--_Haplophlebium Barnesi_, a Carboniferous
insect, from the Coal-meastures of Nova Scotia. (After Dawson.)]

In addition to the water-inhabiting group of the Crustaceans, we
find the articulate animals to be represented by members belonging
to the air-breathing classes of the _Arachnida, Myriapoda_, and
_Insecta_. The remains of these, as might have been expected, are
not known to occur in the marine limestones of the Carboniferous
series, but are exclusively found in beds associated with the Coal,
which have been deposited in lagoons, estuaries, or marshes, in
the immediate vicinity of t