356 Phillips . — On the Development of 
in the neighbourhood of the tuft at this stage, that I failed 
to decide this point, though I examined many sections. 
In the later history of the cystocarp the large-celled outer 
tissue loosens and gives way before the enlarging gonimoblast- 
filaments, forming the cystocarpic cavity. The small-celled 
tissue becomes a kind of placenta lining the base and sides 
of this cavity. 
There would seem to be close relationship between Sphae- 
rococcaceae and Rhodymeniaceae, and a remoter connexion 
between both families and Rhodomelaceae. 
Antithamnion Plumula, Thur. 
It is to the Ceramiaceae, standing as they do, by general 
consent, nearest to the Rhodomelaceae, that I have devoted 
most attention ; and among the species of Ceramiaceae which 
I have examined, none exhibit a simpler structure in the 
cystocarp than Antithamnion Plumula. 
The carpogonial branch arises on the proximal joints 
of the pinnae close behind the apex (PI. XVI II, Fig. n). The 
branch arises laterally, its cells are smaller than the ordinary 
vegetative cells, and it curves round the joint-cell upon which 
it is produced, so that the carpogonium itself rests upon 
it above, and the long trichogyne stretches forward so as to 
overtop the densely aggregated branches near the apex of 
growth. The carpogonial branch is not free, but is throughout 
adherent to the joint-cell from which it is derived. 
Fertilization having taken place, the fertile joint-cell, or 
basal cell, as it may be called, cuts off a lateral cell above 
in close contiguity with the carpogonium. Of the conjugation 
which ensues between these cells, I have no doubt, as I have 
seen the stout ooblastema-tube more than once, and demon- 
strated its presence to others (PL XVIII, Fig. 12 ). In a species of 
Callithamnion in which Schmitz (’92) observed this conjugation, 
he describes it as being effected by means of a small cell cut off 
from the carpogonium. Though I have not been able to satisfy 
myself of the existence of any cell-wall in the carpogonium, 
