\My"sis\, n. [NL., fr. Gr. ? a closing of the lips or
eyes.] (Zo["o]l.)
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.