PLATE I. 



Figs. i — 6. Halimcda Tuna. 



Fig. i . Forma typica, nat. size. 



Fig. 2. Forma platydisca (Canaries. Type of H. platydisca Decaisne). Nat. size. 



Fig. 3. Forma Albcrtisii (Funafuti). Nat. size. 



Fig. 4<2 and b. Filaments of central strand shewing mode of fusion. x 65. 



Fig. 5. Peripheral cells, surface view. 140. 



Fig. 6. Peripheral cells, longitudinal view. ■ 140. 



Figs. 7 — 14. Halimcda cuneata. 



Fig. 7. Forma typica. (South Africa.) Nat. size. 



Fig. 8. Forma typica. Fragment shewing sessile joints. Nat. size. 



Fig. 9. (Plate II.) Forma digitata. (Siboga-Exp.). Nat. size. 



Fig. 10. Forma undulata. (Siboga-Exp.). Nat. size. 



Fig. 1 ia. Several fusing filaments from periphery of central strand, shewing scars which have 

 almost exactly the appearance of pits. The filaments are seen fusing in pairs above 

 and continuing their course in the node as single thick-walled tubes, x 140. 



Fig. \\b. Two fusing filaments from middle of strand. • 65. 



Fig. 12. Optical transverse section through apex of plant just below the ends of the fused 

 filaments, shewing a portion of central strand and adjacent peripheral cells. / 140. 



Fig. 13. Peripheral cells, surface view. 140. 



Fig. 14. Peripheral cells, longitudinal view. 140. 



