lunule: An impressed area just below the beaks of bivalve shells.
The lunule is large and ribbed; the teeth are small; the color is pure white, with a light straw-tinted epidermis.
Legs deep rufous; antenn black; the club beneath and lunule round the eye straw-coloured.
There is no lunule, but a large external ligament is very prominent just back of the beaks.
The lateral teeth are the stronger, and the lunule is upon the right valve only.
lunula lu·nu·la (lōōn'yə-lə)
n. pl. lu·nu·lae (-lē')
A small crescent-shaped structure or marking, especially the proximal region at the base of a fingernail that resembles a half-moon.