The most
famous locality for these great Crustaceans is Lesmahagow, in
Lanarkshire, where many different species have been found. The
true King-crabs (_Limuli_) of existing seas also appear to have
been represented by at least one form (_Neolimulus_) in the Upper
Silurian.
[Illustration: Fig. 65.--_Pterygotus Anglicus_, viewed from the
under side, reduced in size, and restored. c c, The feelers
(antennae), terminating in nipping-claws; o o, Eyes; m m,
Three pairs of jointed limbs, with pointed extremities; n n,
Swimming-paddles, the bases of which are spiny and act as jaws.
Upper Silurian, Lanarkshire. (After Henry Woodward.)]
Coming to the _Mollusca_, we note the occurrence of the same
great groups as in the Lower Silurian. Amongst the Sea-mosses
(_Polyzoa_), we have the ancient Lace-corals (_Fenestella_ and
_Retepora_), with the nearly-allied _Glauconome_, and species
of _Ptilodictya_ (fig. 66); whilst many forms often referred
here may probably have to be transferred to the Corals, just as
some so-called Corals will ultimately be removed to the present
group.
[Illustration: Fig. 66.--Upper Silurian Polyzoa. 1, Fan-shaped
frond of _Rhinopora verrucosa_; 1a, Portion of the surface of
the same, enlarged; 2 and 2a, _Phoenopora ensiformis_, of the
natural size and enlarged; 3 and 3a, _Helopora fragilis_, of
the natural size and enlarged; 4 and 4a, _Ptilodictya raripora_,
of the natural size and enlarged.
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