Development of ascospore appendages was examined in the marine sp. Corollospora maritima. Equatorial fibers develop by fragmentation of an exospore which originally included spore as well as apical thorns. This finding differs from that of earlier authors. At maturation that part of the exospore covering the thorns inverts forming tubes or lobes and, finally, fibers attached to the tip of the thorns. Lateral fibers remain attached to the belt of exospore origin which surrounds the septum. Ascospores of C. lacera and C. comata were collected in the foam along the seashore. Appendage formation in these spp. also occurs by fragmentation of an exospore. The significance of these findings for the taxonomy of Corollospora is discussed.