from the GNU version of the Collaborative International Dictionary of English
- n.pl. A division of bivalve shells, including the marine mussels, in which the two adductor muscles are very unequal. See dreissena, and Illust. under byssus.
from The Century Dictionary and Cyclopedia
- A group of acephalous conchiferous mollusks, including the Mytilidæ, or mussels and related forms: distinguished from Dimyaria and Monomyaria.
Sorry, no etymologies found.