252
SOME NOTES OF THE STALK-EYED CRUS-
TACEA OF THE BRITISH COASTS AND
REFERENCES TO ESSEX FORMS.
Abstract of an Address delivered by Mr. Edward Lovett, at a
Meeting of the Club on February 14th, 1900.
The Stalk-eyed (Decapoda or "ten-legged" Crustacea) are
divided into three groups, viz., the Brachyura or true Crabs,
the Macroura or true Lobsters, Shrimps, and Prawns, and the
Anomoura, embracing representatives of each of the former as
illustrated by the Stone-Crab Lithodes and the Lobster-like
Galathea for example ; as also the Hermit-Crabs. One peculiar
characteristic, however, is that the fifth pair of legs are rudi-
mentary, and are, in fact, merely brushes, and are so used
by the animals in several instances.
Of the Brachyura the best known species, and in most cases
the only popularly known species, are the Edible Crab, Cancer
pagurus, and the Shore Crab, Carcinus mantis ; the majority of
the other British forms being seldom seen near the high-water
mark.
The Spider Crabs of the genera Stenorhyncus and Inachus
are very delicate in structure, and occur in deep water in the
western parts of the Channel ; Stenorhyncus rostratus is
common in the Thames Estuary [and the Colne Estuary, Ed.]
A more robust form Hyas araneus (and its near relative H.
coarctatus) are the typical Essex "Spiders," as the members of
the genus are always found on a sandy or muddy bottom, to
which the colour of the crabs almost invariably corresponds.
Another robust "Spider" form is Pisa gibbsii. This
species has its carapace covered with a dense mass of short fine
spines, forming a sort of "pile." Thus by catching and
entangling bits of Algae, spores of sponges, &c., it acquires a
perfect growth of such plants, so that the animal is thereby pro-
tected from its enemies, the fishes, which although ready to eat
any Crustaceans are averse to sponges and like growths.
Curiously enough this very protection sometimes brings
about the destruction of the Crab, for the sponge growths
gradually cover the whole animal until its death is brought
about. [Specimens were exhibited to illustrate this.]