The Collaborative International Dictionary of English v.0.48:
Mysidacea \Mysidacea\ prop. n. An order of crustaceans including the opossum shrimp. Syn: order Mysidacea. [WordNet 1.5]WordNet (r) 3.0 (2006):
Mysidacea n 1: opossum shrimp [syn: Mysidacea, order Mysidacea]