[Perh. a specific application of prec.: cf. the analogous pair CLAM sb.1, 2]

1

  † 1.  An earlier name of the edible Clams of N. America.

2

1634, 1672.  [see CLAM sb.2 1 d].

3

  2.  Usually Clamp-shell: the large bivalve shell of the tropical mollusks Chama and Tridacna (Family Chamaceæ).

4

1835.  Kirby, Hab. & Inst. Anim., I. viii. 251. The giant Clamp-shells … sometimes four feet in length and weighing more than five hundred pounds suspend their vast bulk by means of a strong byssus.

5

1847.  Carpenter, Zool., § 952.

6