138 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



2. Plants with branches above clearly flattened, although terete 

 below o 



3. Cortex homogeneously filamentous, composed only of extended 

 assimilatory filaments; supporting cells undifferentiated, tumid 

 basal cells absent G. filamentosa 



3. Cortex heterogeneous, composed of extended and of short assimi- 

 latory filaments ; extended assimilatory filaments barbate, or oc- 

 curring in rings 4 



4, Short assimilatory filaments not mixed with long filaments, al- 

 though these may occur at branch bases or on proliferous branches; 

 short filaments composed of an enlarged basal cell and a narrow 

 cylindrical or obconical stalk cell bearing one oval external cell, 



or two cells side by side G. barbata 



4. Short assimilatory filaments sometimes mixed with long fila- 

 ments, sometimes zonate or in groups; short filaments composed 

 of a swollen basal cell, sometimes on a swollen supporting cell, 

 outwardly bearing one rounded cell, or two cells in a filament 5 



5. Short assimilatory filaments two celled G. ramulosa 



5. Short assimilatoiy filaments two or three celled . G. subf ruticulosa 



6. Cortical tissue 20-60 [x thick, 1-2-stromatic; plants small, fru- 

 tescent; branches sometimes constricted, or proliferous, the con- 

 strictions and proliferations at the base surrounded by tufts of 

 extended assimilatory filaments G. stupocaulon 



6. Cortical tissue 60-80 [x thick, 2-3-stromatic ; plant tall, arbor- 

 escent, branches continuous, rarely proliferous . . G. spathulata 



7. Branches terete throughout, cortical tissue parenchymatous or 

 subfilamentous 8 



7. Branches terete only at the base, above flattened; cortical tissue 

 parenchymatous ; lobed cells when present in the median layer 9 



8. Branches villous, cortical tissue parenchymatous, tristromatic, 

 lobed cells present among the cells of the innermost layer . . 

 G. squalida 



8. Branches glabrous, cortical tissue subfilamentous, the cells re- 

 maining attached to the medullary filaments after decalcification 

 G. oblongata 



9. Epidermal cells spinulose, bearing small unicellular subcj'lindri- 

 cal spinelike cells ; cortical tissue containing lobed cells present 10 



9. Epidermal cells smooth, without spinelike cells upon them; 

 cortical tissue with or without lobed cells 11 



10. Thallus 1-2 mm wide, chalky; epidermis abundantly spinulose 

 G. veprecula 



