The Collaborative International Dictionary
Inequivalvular
Inequivalve \In*e"qui*valve\, Inequivalvular \In*e`qui*val"vu*lar\, a. (Zo["o]l.) Having unequal valves, as the shell of an oyster.
Wiktionary
inequivalvular
a. (context zoology English) Having unequal valves; inequivalve.