252 Puget Sound Marine Sta. Pub. Vol. 1, No. 25 



NN. Stipe creeping, rhizome-like; in older forms stipe ab- 

 sent and base of blade with hapteres; blade without 2 

 rows of cross folds, mucilaginous. 



12. Hedophyllum (p. 266) 

 MM. Blade with 3 to 5 longitudinal folds. 



13. Cymathere (p. 267) 

 II. Plant composed of a regular or irregular thin blade; without dis- 

 tinct stipe; usually not over 3 or 4 dm. long; holdfast pad-like. 

 O. Blade narrow, regular, smooth, sporangia over entire surface. 



14. Fhyllitis (p. 267) 

 00. Blade broad, irregular, sporangia in scattered spots. 



15. Punctaria (p. 268) 

 HH. Plant body composed of a sac, a tube, or an irregular mass. 

 P. Plants sac-like, mostly epiphytes on other algae. 



Q. Sac covered with small spots over entire surface, oval, usually 

 expanded and filled with water. 16. Soranthera (p. 269) 



QQ. Sac not covered with small spots, smooth or wrinkled. 

 R. Sac long, 2 or more times as long as wide. 



17. Coilodesme (p. 269) 

 RR, Sac globose or irregular, about as long as wide. 



S. Plant body composed of 2 distinct layers, the inner layer 

 of large rounded cells, the outer layer of more or less 

 cubical cells. 18. Colpomenia (p. 271) 



SS. Plant body not composed of 2 distinct layers of cells, 

 the central part of the plant body composed of re- 

 peatedly-branching dichotomous filaments which termi- 

 nate in the outer cells. 19. Leathesia (p. 271) 

 PP. Plant body composed of a single tube. 



T. Tubes constricted, not twisted. 20. Scytosiphon (p. 271) 



TT. Tubes not constricted, twisted. 21. Myelophycus (p. 271) 

 PPP. Plants forming small crusts or spots on rocks or other algae; 

 composed of microscopic filaments. 

 U. Plants forming small spots on other algae. 



22. Myrionema (p. 272) 

 UU. Plants forming small leathery brown patches or crusts on 

 rocks 23. Rolfsia (p. 273) 



GG. Plants branched. 



V. Plants with one or more air bladders or swollen tips. 

 W. Plants large, 3-20 meters or more when mature. 



X. Plant with one large air bladder on the end of a long tapering 

 terete stipe; blades all branching from bladder. 



24. Nereocystis (p. 273) 



XX. Plant with many small air bladders between the blades on 



each side of the several strap-like branches of the stipe and 



blade. 25. Egregia (p. 274) 



XXX. Plant with many small air bladders, 1 on the base of most 



of the blades; stipe terete, branched. 



26. Macrocystis (p. 274) 



