152 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



axes, or in special lateral branchlets, generally without being arranged in 

 any definite order; spermatangia forming a coating on local areas of the 

 branches; carpogenic branches three celled; cystocarps bilocular, a sterile 

 septum separating two groups of carpospores which discharge from pores 

 on opposite sides of the branchlet. 



KEY TO SPECIES 



1. Plants minute, creeping, or at most turflike and 1-3 cm tall 2 



1. Plants large, bushy, generally 5 cm tall or more when full grown 

 5 



2. Tetrasporangial branchlets with a thickened margin ; in sections 

 a median series of notable large thick-walled cells evident . . 

 G. sclerophyllum 



2. Tetrasporangia not in thick-edged branchlets ; no especially large 

 cells in the medulla 3 



3. Tetrasporangial branchlets irregularly palmately or digitately 

 expanded from a contracted base G. galapagense 



3. Tetrasporangial sori in ordinary branches 4 



4. Very small, about 1 cm tall, rather fleshy G. isabelae 



4. Larger, the thin somewhat nitent blades membranous . . . 



G. pusillum 



4a. Still larger, to 2 cm or by proliferation to 3 cm tall . . . 



V. pacificum 



4b. Blades narrower, when fertile commonly cylindrical, at 



least for the major lower part v. cylindricum 



5. Branchlets with entire margins 6 



5. Branchlets with toothed margins 7 



6. Plants delicate, branches slender, often congested . . G. densum 



6. Plants coarse, cartilaginous . . . G. cartilagineum v. robustum 



7. Axis and primary branches virgate, sparingly divided, dominating 

 the growth habit; determinate branches short pinnate . . . 

 G. Hancockii 



7. Axis and main branches redividing, bushy, progressively pinnate 

 G. filicinum 



Gelidium pusillum (Stackhouse) Lejolis 



Taylor 1928, p. 142, pi. 20, fig. 8, pi. 22, fig. 7, pi. 23, fig. 3. 



These plants are in general rather more vigorous than those which 



