362 Phillips . — On the Development of 
soon found to be a distinct species, and it has now gone into 
a distinct genus. 
The procarps of Plumaria elegans have been described by 
Bornet (’76). He considered them to resemble in all essentials 
the procarps of Callithamnion elegans , which he has figured. 
On account of this similarity he proposed to rename the latter 
plant Ptilota Sckousboei. For this plant, however, Agardh 
(’92) has thought it desirable to found a new genus, Gymno- 
thamnion . The fact remains, that Bornet’s figures of Calli- 
thamnion elegans were regarded by him as illustrating in all 
essentials the case of Plumaria. 
Very recently Davis ( J 96c) has given a full description of the 
development of the cystocarp in three American plants : Ptilota 
serrata , Kiitz (an Atlantic species) ; Ptilota plumosa , C. Ag., 
and Farlow’s variety filicina of Ptilota plumosa C. Ag. (both 
Pacific species). These species are represented by the author 
as being greatly divergent in the morphology of the procarpial 
branches from any other species of Ceramiaceae, and he founds 
upon these peculiarities a theoretical superstructure of great 
interest. 
My own investigations upon the development of the favellae 
in Ptilota plumosa and Plumaria elegans lead me, however, to 
put quite a different interpretation upon the morphological 
characters they present, and to dissent from the theoretical 
conclusions advanced by Davis. 
The procarpial branches of Ptilota plumosa and Plumaria 
elegans are, as in the American species also, smaller pinnae 
alternating with larger vegetative pinnae. Upon these the 
favellae arise in an apparently terminal position, surrounded 
by an involucrate whorl of sterile branches. 
The penultimate cell of the procarpial branch may be seen 
to bulge outwards, i.e. away from the axis upon which the 
procarpial branch is borne. A cell is soon cut off on this 
side, and the apical cell is deflected inwards. From these 
three cells, the apical cell, the sub-apical cell, and the peri- 
pheral cell derived from this sub-apical cell, there now 
arises a group of five branches, each of which ends off in 
