pygidium

The posterior body region or segment of certain invertebrates.

A posterior part of the body, in any way distinguished; an anal, caudal, or pygal part or organ: said chiefly of insects, crustaceans, and worms.

[capitalized] A genus of nematognaths, typical of the family Pygidiidæ. Later called Trichomycterus.

The caudal plate of trilobites, crustacean, and certain insects. See Illust. of limulus and trilobite.

The caudal plate of trilobites, crustacea, and certain insects.