36 Allan Hancock Pacific Expeditions vol. 26 



4. Thalli 4-5 mm. high, uncorticated at the base 



A. sarcodiae B0rg. 



4. Thalli 1 cm. high, lightly corticated at the base 



A. brodiaei (Harv.) Feld.-Maz. 



5. Spermatangia on short lateral branchlets of 4-5 cells 



A. furcellariae (J. Ag.) Feld-Maz. 



5. Spermatangia sessile, in pulvinate groups on the branchlets 6 



6. Ultimate branches with cells about 5 diameters long; carpo- 

 gonial branch zig-zag; gonimoblast very irregularly 3- 

 lobed A. neglectum Feld.-Maz. 



6. Ultimate branches with cells about 10 diameters long; 

 carpogonial branch "U" shaped; gonimoblast irregularly 

 heart-shaped A. cordatum (Borg.) Feld.-Maz. 



7. Branching tri-pinnate in one plane 



A. tripinnatum (Grat.) Feld.-Maz. 



7. Branching multifarious below, pinnate above 8 



8. Tetrasporangia subspherical ; branching pinnate or secund 

 above " 



8. Tetrasporangia oblong; branching subdichotomous above .... 



A. tenuissimum (Bonnem.) Feld.-Maz. 



9. Branching sparse above, often unilateral 



A. caudatum (J. Ag.) Feld.-Maz. 



9. Branching regularly pinnate above 



A. scopulorum (J. Ag.) Feld.-Maz. 



Aglaothamnion cordatum (B0rg.) Feldmann-Maz. 

 PL 12, fig. 1-3 

 Feldmann-Mazoyer 1940, p. 459. Callithamnion cordatum Bergesen 1909, p. 

 10; Borgesen 1917, p. 216, fig. 201-207. 



Thalli epiphytic, about 2 (to 4) cm. tall, forming delicate tufts; 

 principal axes 100-150 ju, in diam. at the base, attached by slender, 

 little-branched, multicellular rhizoids, the cells 1-2 diameters long near 

 the base, producing a single, slender, descending, closely appressed 

 rhizoid from the basal cell of each lateral branch; axial cells longer 

 above, 3-6 diameters long, gradually attenuated through successive 

 branch orders; principal branching regularly alternate, spiral, from the 

 distal end of axial cells, the basal cell of a lateral branch often much 

 smaller in diameter than the axis; lateral branches with 4 or more 

 orders of dichotomous branches, the ultimate ones of 3-7 cells, 50-70 /x 

 long, 7-10 fi in diam., with minutely blunt tips, all ascending and 

 inwardly curved; tetrasporangia scattered throughout the upper 

 branches, adaxial, sessile, at first clavate then ovoid, 40-50 p long; 

 spermatangia borne in pulvinate, adaxial clusters along branchlets of 



