ich became a cobweb, while Arachne herself was changed into a
spider (Ovid, _Metam_. vi. 5-145). The story probably indicates the
superiority of Asia over Greece in the textile arts.

ARACHNIDA, the zoological name given in 1815 by Lamarck (Gr. [Greek:
harachnae], a spider) to a class which he instituted for the reception
of the spiders, scorpions and mites, previously classified by Linnaeus
in the order Aptera of his great group Insecta. Lamarck at the same time
founded the class Crustacea for the lobsters, crabs and water-fleas,
also until then included in the order Aptera of Linnaeus. Lamarck
included the Thysanura and the Myriapoda in his class Arachnida. The
Insecta of Linnaeus was a group exactly equivalent to the Arthropoda
founded a hundred years later by Siebold and Stannius. It was thus
reduced by Lamarck in area, and made to comprise only the six-legged,
wing-bearing "Insecta." For these Lamarck proposed the name Hexapoda;
but that name has been little used, and they have retained to this day
the title of the much larger Linnaean group, viz. Insecta. The position
of the Arachnida in the great sub-phylum Arthropoda, according to recent
anatomical and embryological researches, is explained in the article

ARTHROPODA. The Arachnida form a distinct class or line of descent in
the grade Euarthropoda, diverging (perhaps in common at the start with
the Crustacea) from primitive Euarthropods, which gave rise also to the
separate lines of descent known as the classes Diplopoda, Crustacea,
Chilopoda and Hexapoda.

[Illustration: FIG. 1.--Entosternum, entosternite or plastron of
_Limulus polyphemus_, Latr. Dorsal surface.

LAP, Left anterior process. PLR, Posterior lateral rod or
RAP, Right anterior process. tendon.
PhN, Pharyngeal notch. PLP, Posterior lateral process.
ALR, Anterior lateial rod or tendon. Natural size.

(From Lankester, _Q J. Mic. Sci._, N S vol. xxiv, 1884)]

_Limulus an Arachnid._--Modern views as to the classification and
affinities of the Arachnida have been determined by the demonstration
that _Limulus_ and the extinct Eurypterines (_Pterygotus_, &c.) are
Arachnida; that is to say, are identical in the structure and relation
of so many important parts with _Scorpio_, whilst differing in those
respects from other Arthropoda, that it is impossible to suppose that
the identity is due to homoplasy or convergence, and the conclusion must
be a