EARLY DEVELOPMENT AND MORPHOGENESIS OF THE INTRACAPSULAR VELIGER OF HAMINAEA-NAVICULA (GASTROPODA, OPISTHOBRANCHIA, BULLOMORPHA)

1The development of Haminaea navicula was studied by anatomical and hi stological methods. This species shows typical spiral cleavage, which leads to a stereoblastula Gastrulation is reached by epiboly. A fully developed veliger larva is reached within the egg capsule that is not only capable of swimming when artificially hatched but is also provide d with the same larval organs (larval shell, velum, operculum, larval cephalic sensory organ, anal cells, anal gland, nephrocyst-protonephri dial complex, epipodial and pallial gland cells) that are present in p elagic larvae of related species. Aspects of the development of H. nav icula are compared with observations of the pelagic larvas of H. exigu a and H. vesicula. Additional data from the literature are discussed.