288 PERCY SLADEN TRUST EXPEDITION 
habit, having a well defined stem and regularly placed lateral branches, whereas Hndo- 
siphonia has no definite stem nor regular ramification. Anatomically the genus is 
characterized by its four big pericentral cells (fig. 30, p.c.), surrounded by several layers 
of cortical cells which are always much smaller. In Endosiphonia the four pericentral 
cells are surrounded by cells of the same size. 
The stem of Pseudendosiphonia is attached to small flat stones or particles of rock 
by means of small rhizoids and around it stand four branches with a divergence of 7; 
they take their origin from the central cell and are therefore endogenous; the lateral 
ones are of unlimited growth (Langtriebe), the dorsal and ventral ones remain short 
(Kurztriebe). The lateral branches have the same development as the principal stem, 
but their side-branches remain at first short and give the plant a thorny appearance 
that strongly reminds one of Endosiphonia. At the top of some branches there are 
luxuriously developed trichoblasts (“ leaves,” Falkenberg), but on most they had fallen 
off, probably because they have so many side-branches and such large cells. 
The stichidia bear a great resemblance to those of Hndosiphonia, particularly to 
E. clavigera, for they are placed irregularly on the stem and branches (Pl. 1%. fig. 14) 
and not in the axils of the latter. They spring from peripheral cells and have a mono- 
siphonous pedicel, but this bears branches, which is not the case with #. clavigera. The 
stichidium itself was bare in all the specimens examined, but I think it likely that the 
branches of the pedicel may develop further stichidia. I noted at the top of these 
branches some divided cells that I thought would develop into stichidia, but no later 
stages were observed. The cells covering the tetraspores in the stichidium are not 
horizontally disposed as in Hndosiphonia but are arranged more or less obliquely. It is 
not certain, however, how far this may change as the sporangium attains maturity. 
This alga differs from the genus Hndosiphonia by its habit and anatomical structure, 
and though nearly related to it, I believe I am justified, on account of these differences, 
in describing it as a new genus. 
I have great pleasure in dedicating this interesting species to Mr. J. Stanley 
‘Gardiner. 
CLADHYMENIA, Hooker et Harvey. 
1. CLADHYMENIA OBLONGIFOLIA, Hook. et Harv. (Plate 16. fig. 7.) 
Hooker et Harvey, Alg. Nov. Zel. no. 70. 
De Toni, Syll. Alg. vol. iv. sect. m1. 1903, p. 850. 
Amirante, 25 fms.; dry specimens and in alcohol. 
Distribution. New Zealand. 
The specimens from Amirante are small (Pl. 16. fig. 7) but identical with some that I 
received from Prof. J. Agardh from New Zealand under the name of Cladhymenia 
oblongifolia, var. I think that the small size of the Amirante specimens may be 
accounted for by the great depth from which they come. 
