pty cha canthus

[Pref. ptych-, and Greek a kantha a spine.] Palæont .: A genus of Plagiostomous Fishes, with two species from the Lower Devonian of Here ford shire and Mon mouths hire, and one from the Coal measures near Edinburgh. pty-chō-, ptych-, pref. [Greek ptyx (gen it. pty chos) =a fold, leaf, layer, or plait.] Nat. Science: Having a proce or proce es like a fold, leaf, layer, or plait. pty-choç'-er-ăs, subst . [Pref. ptycho- , and Gr. keras a horn.] Palæont .: A genus of Ammon i tide. The shell bent once upon itself, the two straight portions in contact Eight species. From the Neocomian to the Chalk of Britain, France, and India. ( S. P. Woodward.) pty-chōde, subst. [Pref. ptych-, and Gr. eidos = form.] Nat. Science: A membrane within a cell; protoplasm.