556 BULLETIN OF THE BUREAU OF FISHERIES. 
sporangium 670. 7. Short exterior filaments670. 8. A branched exterior filament showing lateral 
and terminal sporangia (one of the emptied lateral sporangia is apparently being refilled or regene- 
rated from the supporting vegetative cell) 670. 9. Ashort exterior filament showing regeneration 
of a terminal sporangium 670. 10. Part of a plant showing mode of branching and tortuous course 
of a part of an interior filament, etc.<670. 11. A short exterior filament bearing immature and 
emptied sporangia X670. 12. An unusually long exterior filament showing long hairs and short secund 
branchlets (solitary or in pairs)X670. Drawings by M. A. Howe, from Howe and Hoyt, 1916. 
PLateE CXIX: Acrochetium affine; 1. Spore attached to margin of the Dictyota thallusX415. 2. Aspore 
that has developed a small accessory prostrate basal cell and is also beginning to send up an erect 
filamentX415. 3. Base of amature plant showing simple basal cell and two erect filaments, each of 
which branches from its lowest cellX415. 4. Base of asimilar, though larger, plant with four primary 
erect filaments, each branched at its base, a small cystocarp shown at a X415. 5. Base of a plant 
showing a scarcely enlarged basal cell, short creeping basal filaments, and a single erect filament 
which has two branches from its lowest cellX415. 6. A vertical section through the base of a plant, 
showing a few small accessory cells that partly cover the primary basal cellX415. 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 415. 8. Base of a plant with accessory basal cells and erect filaments 
of various sizes 415. 9. Base of a plant that has developed a small imperfect basal disk, with the 
original spore still evident 415. 10. Optical section of the margin of the Dictyota thallus showing 
base of a young plant with a single immersed basal cell and a single erect filament X415. 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 filamentsX415. 12. Section 
through the margin of the Dictyota thallus showing single subpyriform basal cell with penetrating 
foot 415. 13. Base of a detached plant showing primary basal cell, its penetrating foot, three 
erect filaments, and two small accessory basal cells 415. 14. Section of margin of the Dictyota 
thallus showing four basal cells of approximately equal size that are more or less immersed X 415. 
15. Asporangium terminal on a main branchX415. 16. Sessile lateral sporangiaX415. 17. Aspo- 
rangium on a one-celled pedicel 415. 18, Procarp and antheridiaX670. 19. An older procarp 
with no antheridia apparent in its vicinityX670. 20. A cystocarpX670. 21. A typical cell from 
one of the coarser filamentsX670. 22. A typical cell from one of the more slender filaments X 670, 
Drawings by M. A. Howe, from Howe and Hoyt, 1916. 
