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Webster 1913 Edition

Noun.

[

Ortho-

+ Gr. [GREEK], [GREEK], a horn.]

(Zool.)

An orthoceras; also, any fossil shell allied to Orthoceras.

Noun.

[Gr. straight, and a horn.]

The name of certain fossil univalve shells, straight or but slightly curved, arranged by Cuvier in the genus Nantilus.

orthoceratite ‎(plural orthoceratites)