26 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 26 



15. Ultimate branchlets becoming prominently recurved in age .... 16 



15. Ultimate branchlets remaining ± incurved throughout 17 



16. Lateral branchlets at first overarching, forcipate, later 



recurved and unicinate C. uncinatum sp. nov. 



16. Lateral branchlets only incurved at first, not forcipate, 

 later recurved but not uncinate .. C. rupicolum Anderson 



17. Tetrasporangia sessile and solitary 18 



17. Tetrasporangia multiple and pedicellate .... C. biseriatum Kylin 



18. Ultimate branchlets 15-20 fi in diam 



C. paschale Borgesen (The Japanese C. 



minutissima Yamada is similar and possible conspecific) 



18. Ultimate branchlets (40) 50-65 [jl in diameter 19 



19. Cells of lower main axes about as long as broad 



C. pacificum Taylor 



19. Cells of lower main axes 3.5 diameters long 



C. soccoriense Taylor (in part) (Variation 



in this species makes distinction from C. pacificum uncertain) 

 20. Ultimate branchlets short, of 1-4 cells, commonly ending 



in a deciduous hair C. corymbosum 



20. Ultimate branchlets longer, of 5 or more cells, without 



terminal hairs 21 



21. Ultimate branchlets relatively coarse, about one half the 



diameter of the main axes, or more 22 



21. Ultimate branchlets slender, 1/3 to 1/10 the diameter of the 



main axes 23 



22. Plants 1-2 mm tall, of compact form, arising from a 



multicellular disc C. compactum sp. nov. 



22. Plants about 1 cm. tall, of loose form, attached by 



rhizoids C. rigidum sp. nov. 



23. Plants much attenuated from the base (170-300 ju,) to the 



tips (8-10 ju), abundantly and densely branched above 



C. ramosissimum Gardner 



23. Plants not so much attenuated, the ultimate branchlets about 

 14 the diameter of the axes, more or less openly branched 



above 24 



24. Lateral branchlets ascending, 30-20 [x in diameter 



C. marshallense Dawson 



24. Lateral branchlets divaricate, attenuated from 15-10 to 

 8-4.5 fi in diameter C. epiphyticum Taylor 



Callithamnion bisporum var. australe var. nov. 

 PI. 9, fig. 4 

 Thalli c. 1 cm. alt., ex axibus paucis ramosis, per rhizoidea multicellularia 

 affixis, constantes; axes erecti non-percurrentes ecorticati, ad basim ad 200 (j. 



