HOWE AND HOYT: MARINE ALGAE FROM BEAUFORT, N. C. I23 



3. Base of a mature plant, showing simple basal cell and two erect filaments, each 

 of which branches from its lowest cell. 



4. Base of a similar, though larger plant, with four primary erect filaments, each 

 branched at its base. A small cystocarp at a. 



5. Base of a plant showing a scarcely enlarged basal cell, short repent basal fila- 

 ments, and a single erect filament which has two branches from its lowest cell. 



6. A vertical section through the base of a plant, showing a few small accessory 

 cells that partly cover the primary basal cell. 



7. Base of a plant showing accessory basal cells and three coarse and three slender 

 erect filaments, none of which branches from its lowest cell. 



8. Base of a plant with accessory basal cells, and erect filaments of various sizes. 



9. Base of a plant that has developed a small imperfect basal disc, with the original 

 spore manifest. 



10. Optical section of the margin of the Dictyota thallus, showing base of young plant 

 with a single immersed basal cell and a single erect filament. 



11. Optical section of the base of a plant, showing subpyriform semi-immersed 

 primary basal cell and several superficial smaller secondary cells, some of which send 

 up erect filaments. 



12. Section through the margin of the Dictyota thallus, showing single subpyriform 

 basal cell with penetrating foot. 



13. Base of a detached plant showing primary basal cell, its penetrating foot, three 

 erect filaments, and two small accessory basal cells. 



14. Section of margin of the Dictyota thallus, showing four basal cells of approxi- 

 mately equal size that are more or less endophytic. The partly overlying cortical cells 

 of the Dictyota are for the most part disintegrated, but this may have been accomplished 

 by agencies other than the Acrochaetium. 



15. A sporangium terminal on a main branch. 



16. Sessile lateral sporangia. 



17. A sporangium on a one-celled pedicel. 



18. Procarp and antheridia. 



19. An older procarp with no obvious antheridia in its vicinity. 



20. A cystocarp. 



21. A typical cell from one of the coarser filaments, showing chromatophores and 

 parietal pyrenoid. 



22. A typical cell from one of the more slender filaments. 

 Figures 1-17 are enlarged 415 diameters; 18-22, 670 diameters. 



