Cyst o carp in Rhodomelaceae (//). 201 
general ; carpogonial branch ; sterile branches ; auxiliary cell ; 
paranematal filaments ; and the pericarp. 
Procarp . — A modified leaf in all cases (except Dasya ), the 
second joint of which is the fertile joint. In Dasya the pro- 
carp is axial. 
Carpogonial branch. — Invariably four-celled, arising from 
the fifth pericentral cell, and curving so as to bring the 
carpogonium near to the cell from which it arises. 
Sterile branches .— Two such branches arising from the peri- 
central cell — one in the inferior position, one in a lateral 
position — are invariably present. 
In Rhodomela and Polysiphonia the inferior branch is one- 
celled, the lateral branch is two-celled at fertilization of the 
trichogyne, becoming respectively two-celled and four-celled 
later. 
In Chondria and Laurencia both branches are luxuriantly 
branched into tufts of filaments at the time of fertilization, 
developing but little afterwards, and becoming partially 
absorbed on spore-formation. 
In Dasya the two branches are represented but slightly, if 
at all, at the time of fertilization, but become richly branched 
afterwards, still before spore-formation sets in. 
Auxiliary Cell. — In Rhodomela , Polysiphonia , and Dasya 
there is cut off from the pericentral cell, a superior cell 
which is the auxiliary cell and conjugates with the carpo- 
gonium. In A thuyoides this cell is cut off before fertilization 
of the trichogyne, usually immediately after, in Dasya long after. 
In Chondria and Laurencia it would seem that the peri- 
central itself acts as the auxiliary cell. 
Paranematal filaments. — These derivatives of the central cell 
are invariably present, and line the cavity of the cystocarp. 
In Rhodomela and Polysiphonia they are few in number 
and widely separated. 
In Chondria and Dasya they form a continuous layer, often 
more than one cell deep. 
In Laurencia they are several cells deep, the inner then 
becoming more attenuated than the deeper seated. 
