60 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



19. Branching mostly irregularly alternate, the ultimate branchlets 



not appearing particularly regular 20 



20. Tetrasporangia borne in short, clavate, ultimate branchlets 



G. pulchrum 



20. Tetrasporangia borne in elongated sori in ultimate and 

 subultimate branchlets with prominent sterile margins 



G. sonorense 



21. Plants small, less than 2 cm. high 22 



21. Plants larger, 10-25 cm. high 23 



22. Erect branches usually simple; tetrasporangia borne in 



decussate rows P. caloglossoides 



22. Erect branches 1-2 times pinnate; tetrasporangia unknown 



P. parva 



23. Cystocarps borne singly at the base of ultimate branchlets; 

 tetrasporangial sori linear, extensive . . P. cornplanata 

 23. Cystocarps borne singly in the distal part of ultimate branch- 

 lets ; tetrasporangial sori elevated, but not linear or particular- 

 ly extensive P. pyramidal e 



24. Branches expanded and flattened above, ligulate 



Gdl. ligulata 



24. Branches cylindrical or compressed 25 



25. Primary branches to 1 mm. in diameter; plants to 5 cm. high 



Gdl. acerosa 



25. Primary branches 40-300 /a in diameter; plants 1-15 mm. high 26 

 26. Branches cylindrical throughout; reproduction by tetra- 

 sporangia arranged irregularly in slightly swollen short 



branchlets Gdl. hancockii 



26. Branches cylindrical to compressed ; reproduction by tetra- 

 sporangia arranged regularly in four ranks in terminal 



stichidia Gdl. stichidiospora 



26. Branches subcylindrical to compressed ; reproduction ap- 

 parently by large monospores? 20-50 /a in diameter in 

 cortical cavities of short, acute terminal branchlets 



Gdl. refugiensis 



27. Thalli 250-850 /^ in diameter; cells of medullary core 12-20 



diameters long Gclidiopsis 28 



27. Thalli 150-220 p. in diameter; cells of medullary core 7-10 



diameters long Wurdemannia miniata 



28. Thalli to 6 cm. high; segments 250-400 /a in diameter 



Gps. tenuis 



28. Thalli to 16 cm. high; segments 500-850 ju, in diameter 

 Gps. variabilis 



