diastylidæ

Century Dictionary and Cyclopedia

1. A family of macrurous thoracostracous crustaceans, equivalent to the suborder Cumacea of some authors, containing remarkable annectent forms related on the one hand to schizopods, on the other to copepods, and exhibiting in some respects a persistence of a larval type of higher Crustacea. They are Thoracostraca or podophthalmia with a small cephalothoracic shield, typically 5 thoracic somites, 6 pairs of legs, of which at least the two anterior pairs are biramous or of the schizopod type, maxillipeds in 2 pairs, and the abdomen elongated, of 6 somites, and in the male bearing several pairs of swimming-feet besides the terminal appendages. Diastylis and Leucon are leading genera. As understood by recent naturalists, it is limited to Diastylis and Leptostylis; these have the integuments strongly indurated, body and tail sharply defined, and the carapace large and vaulted, with a conspicuous rostriform prominence.