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Relation of Myriopods to Insects.

The mouth-parts of the myriopods are so different in shape and general function from those of insects, that this character, together with the equally segmented nature of the portion of the body behind the head (the trunk), forbids our merging them, as some have been inclined to do, with the insects. There are two sub-classes of myriopods, differing in such important respects that by Pocock^[1] and by Kingsley they are regarded as independent classes, each equivalent to the insects.

Of these the most primitive are the Diplopoda (Chilognatha), represented by the galley-worms (Julus, etc.).

Fig. 5.—Mandible of Julus: l, lacinia; g, galea; p, dens mandibularis; ma, “mala”; lt, lamina tritoria; st, stipes; c, cardo; m, muscle.—After Latzel.

In the typical Diplopoda the head consists of three segments, a preoral or antennal, and two postoral, there being two pairs of jaw-like appendages, which, though in a broad morphological sense homologues of the mandibles and first maxillæ of insects, are quite unlike them in details.