Formation of the lantern of Aristotle of C. subdepressus.

A Rudiments of the lantern after the regression of larval tissues at the end of metamorphosis. Each set of ossicles was intercalated by a rotula (not visible) and consisted of a central tooth (arrow), two demipyramids (arrowheads), and two epiphyses (dashed line). Latter and rotula not visible because of orientation of polarized light. Asterisks mark the epiphyses of the adjacent sets. B Demipyramids (d) were formed, but not sutured together 2 dpm; teeth had narrow tips (arrow). C Demipyramids were tightly sutured into a pyramid (p) 7 dpm. D Mature teeth with ornamentation on the inner side (left). Scale bars =