My"sis (?), n. [NL., fr. Gr. a closing of the lips or eyes.] Zool.
A genus of small schizopod shrimps found both in fresh and salt water; the opossum shrimps. One species inhabits the Great Lakes of North America, and is largely eaten by the whitefish. The marine species form part of the food of right whales.
© Webster 1913.