Bifid, opening with a cleft.

Bilobate, divided into two lobes.

Bimarginate, two margins or lips.

Biradiate, having two rays.

Bivalve, having two valves.

Blunt, obtuse, opposed to acute.

Borer, a piercer.

Bulging, gibbous, swollen out.

Byssus, common in the Mytilus and Pinna, by which they attach themselves to objects.

C.