NO. 1 TAYLOR: PACIFIC MARINE ALGAE 289 



4. Axis relatively stout, bearing lateral determinate branches or 

 branchlets 5 



4. Axis and branches not clearly delimited Polysiphonia 



5. Branching radial 6 



5. Branching bilateral 8 



6. Axis stout, heavily corticated, the determinate branches and 

 branchlets dichotomous, monosiphonous .... Brongniartella 



6. Axis stout, heavily corticated, the polysiphonous branchlets corti- 

 cated at the base 7 



6. Axis more slender, branchlets not crowded, not at all corticated, 



but polysiphonous Bryocladia 



7. Axis completely surrounded by short simple divaricate corticated 

 branchlets Digenia 



7. Axis more loosely beset with short, alternately divided, determi- 

 nate branches Bryothamnion 



8. Branches not compressed, near the tips generally inrolled . . 

 Bostrychia 



8. Main branches compressed, not inrolled near the tips . . . 

 Pterosiphonia 



9. Erect branches simple or subsimple, most likely to branch in the 

 fertile individuals ; dark in color Lophosiphonia 



9. Erect branches simple, relatively short .... Herposiphonia 



LAURENGIA Lamouroux, 1813 



Plants erect, bushy, seldom decumbent, the branches moderately firm 

 to quite fleshy, usually cylindrical, in some species compressed, often 

 alternately branched ; apical cells protected by trichoblasts and sunken in 

 an apical pit; tetrasporangia distributed over the short fertile branchlets 

 at the surface; spermatangia united into paniculate clusters and immersed 

 in the cuplike branch tips ; pericarps sessile on the ultimate branchlets. 



KEY TO SPECIES 



1. Plants minute, chiefly decumbent, with subsimple erect branches 



L. clarionensis 



1. Plants essentially erect 2 



2. Plants small, less than 10 cm tall 3 



2. Plants growing to be more than 10 cm tall 5 



3. Axes and branches grading into the branchlets . . . L. intricata 

 3. Axes and main branches clearly demarcate from the veiy obtuse 



to truncate ultimate branchlets 4 



