inoceramus

Century Dictionary and Cyclopedia

1. n. A genus of fossil bivalve mollusks of the family Aviculidæ, characteristic of the Cretaceous period. The genus was founded by Sowerby. The shell has a long straight hinge furnished with numerous ligamentary pits, and the form is oval or oblong with prominent umbones. The internal layer of the shell is nacreous and the external thick, prismatic, and fibrous. Numerous species are described.

GNU Webster's 1913

1. n. (Paleon.) An extinct genus of large, fossil, bivalve shells, allied to the mussels. The genus is characteristic of the Cretaceous period.