Studies in the Embryology of the Echinoderms

Abstract

ABSTRACT In the following pages I propose to give a comparative account of the structure and development of certain organs in young Echinoderm larvæ. I am not here concerned with the earliest stages (gastrula, &c.), nor with those later ones in which the pentamerous symmetry of the adult is already assumed, but only with that bilaterally symmetrical stage which is more or less clearly represented in all Echinoderm larvæ, and to which Semon (28) has given the convenient name “Dipleurula.”