Thoracostraca

Thoracostraca, or PODOPHTHAMMATA, a sub-class of Crustacea (q.v.), including those in which the eyes are carried at the extremities of flexible stalk-like appendages. The body is protected in front by a carapace or shield, while the animal consists of twenty sgements constructed fundamentally on the same plan, though greatly modified to serve different purposes. The subclass includes four orders:- (1) Cumacea, a group of small forms, not well known popularly, and having no fossil representative; (2) the Schizopoda (q.v.), including the living Opossum Shrimps (Mysis), and probably the Carboniferous fossils Palaeocaris and Gampsonyx; (3) the Stomatopoda (q.v.) or Locust Shrimps, with Diplostylus from the Coal Measures, Sculda from the German Lithographic Stone of Solenhofen, and the many species of the type-genus Squilla as fossil representatives; and (4) the Decapoda (q.v.), the best-known order including the Crabs, Lobsters, and Hermit Crabs.