A nomenclature for the teeth of the radula of fossil and living Cephal
opoda is proposed. The names suggested can be used for the 13 elements
(teeth and plates) across each transverse row of the radula of Nautil
oidea (fossil and extant), and, by retaining the names for all except
the two outer elements on either side, for the nine elements in Ammono
idea (fossil) and Coleoidea (fossil and extant). One transverse row of
the radula has a central rhachidian tooth, and on either side lateral
tooth 1, lateral tooth 2, marginal tooth 1, marginal plate 1, margina
l tooth 2, marginal plate 2, the last two being present only in the Na
utiloidea.