xv, 63 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Living echinoids comprise two major sister clades, the Euechinoidea and the Cidaroidea. Cidaroids first appeared during the lower Permian (~255 mya) and are considered to represent the primitive form of all other living echinoids. The present study of Cidaris blakei, a deep-sea planktotrophic cidaroid urchin, provides a description of development from fertilization through early juvenile stages and is the first report of a deep-sea organism reared through metamorphosis. Cidaris blakei resembles other cidaroids in its lack of a cohesive hyaline layer, the absence of an amniotic invagination for juvenile rudiment formation, and the presence of a single spine morphotype at metamorphosis. Cidaris blakei differs from other cidaroids in the presence of an apical tuft, the extent of fenestration of postoral skeletal rods, the shape of juvenile spines and an extended (14 day) lecithotrophic stage prior to development of a complete gut. This study includes my co-authored materials. / Adviser: Alan Shanks