right angles, followed, in each quadrant so formed, by a wall approximately parallel to one of the first formed walls. Each portion so formed then gave rise to an inner and an outer cell by a fairly regular sequence of walls. There was no constant orientation of the longitudinal axis in relation to the receptacle, as can be seen by comparing the position of the attaching stalks in Text-figs. 4B, D and F. Text-Fig. 4.—Sections and surface views of young sporelings. A, B, C, K and L. C. plumosum var. capillifolium. D—C. flexuosum. E, F, G, H, J—C. maschalocarpum. Except for stage A comparable stages were seen in all three species in which sporelings were found. A, B, C, D and F are median longitudinal sections. E—A surface view of a week-old living sporeling. G, H, J—Transverse sections of the same sporeling of C. maschalocarpum at different levels. K and L—Transverse sections of two sporelings of C. plumosum of slightly different ages showing the regular sequence of wall formation. Outlines drawn with the aid of a camera lucida. Scale = × 140. By this stage the rhizoidal system was well established and the sporeling became detached. It was not possible to judge how long the sporelings remained attached in nature, but in all three species followed, attached sporelings were found which were comparable in size and differentiation with some in cultures of C. maschalocarpum a week after fertilisation. Discussion In the formation of a tongue cell cut off by a curved wall, the species of Carpophyllum investigated resemble other members of the Sargassaceae, of which details are known. Late maturation of the oosphere is characteristic of those Sargassaceae in which the oosphere is retained, and the degeneration in situ of the supernumerary nuclei is also in agreement with other members of the Sargassaceae and in contrast to the condition in the Cystoseiraceae where they are extruded from the cytoplasm.