the Cystocarp in Rhodymeniales. 359 
itself, when the embryo grows at the expense of cells of the 
endosperm. 
In Griffithsia setacea , the fertile branches differ in structure 
from those of Griffithsia corallina and Griffithsia Borne tiana . 
They consist of an axial row of five cells. The first two 
contribute to the formation of the involucre, which here 
consists of two whorls. The third has no lateral outgrowths. 
The fourth gives rise to a whorl of branches of which one 
generates from its proximal cell a typical carpogonial branch. 
The fifth has no further development. Though I did not 
pursue the development of the favella in this species, I believe 
it arises in the same way as in the other species. 
It would thus seem that, while the procarp itself and the 
development of the favella correspond closely in these species 
of Griffithsia with that already described for Antithamnion 
Plumula, yet each presents such marked peculiarities of 
structure in the fruiting-branch taken as a whole, as to make 
it possible, one would suppose, to establish readily distin- 
guishable sub-genera, if nothing more, on this basis in a 
revision of the genus. Considering the great similarity, 
amounting almost to identity, sometimes existing in the 
structure of fertile branches between different genera of 
Ceramiaceae (e.g. Ptilota and Plumaria ), it is remarkable 
that Naegeli’s proposal to found the genus Heterosphondylimn 
to receive Griffithsia corallina and Griffithsia Schousboei has 
not been adopted by later writers. 
Callithamnion granulatum, C. A g., and CALLITHAM- 
NION BYSSOIDES, Arn. 
The procarps of different species of Callithamnion and 
allied genera have been described and figured by Bornet and 
Thuret (76 and 78), Janczewski (76), and Schmitz (’83). 
The cells of which they consist are however so small and 
closely packed that it is difficult to make out their genetic 
relationship : so much so, that Schmitz (’92) amended his 
earlier description on the ground that all other previous 
