4 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



3. Margins irregular, the cells elongate, not bifurcate 



E. irregularis 



4. Mature filaments essentially cylindrical 5 



4. Mature filaments flat, ligulate or ribbon-like ... 9 



5. Attached by a single basal cell 6 



5. Attached by a group of cells 8 



6. Filaments tetraseriate above . . . . E. tetraseriata 



6. Filaments uniseriate or biseriate above 7 



7. Basal cell attenuated, penetrating . . . . E. biseriata 



7. Basal cell lobed E. carnea 



8. Attached by a short, creeping, uniseriate, basal filament 



E. ascendens 



8. Attached by a group of branched, rhizoidal cells 



E. californica 



8. Attached by a monostromatic disc . . . E. ciliaris 



9. Blades arising from a polystromatic, pulvinate basal mound at- 

 tached to the apex of a Codium utricle . E. pulvinatum 



9. Blades arising from a monostromatic, multicellular disc 



E. boryana 



Erythrocladia ectozoica sp. nov. 

 Plate 10, fig. 1 



Thallis epizoicis in Tubularia, 0.5-2.0 mm. longis, unistratosis, fil- 

 amentis uniseriatis biseriatisve irregulariter ramificatis, seriebus cellu- 

 larum irregulariter anastomosantibus, rete plus minusve laxum efficienti- 

 bus, areis raris filamentorum lateraliter compactorum ; cellulis plus 

 minusve angularibus, 7-17 yu, diametro maximo, chromatophorio parietali 

 unico. 



Thalli epizoic and encircling the hyaline tubes of hydroids, irregular- 

 ly ramified, unistratose, consisting of irregularly branched uniseriate or 

 biseriate filaments, in part radiating, but mainly tending to grow in one 

 direction, the cell row^s straight or curved, irregularly anastomosing, 

 forming a more or less open network with occasional areas of laterally 

 compacted filaments; colonies 0.5-2.0 mm. in extent; cells very irre- 

 gularly shaped, more or less angular, mostly 7-17 /i in greatest diameter, 

 with a single parietal chromatophore ; reproduction not observed. 



Type: Holotype is D. 9992, April 16, 1951 in vial 2295 in 

 HAHF. 



