systematic account of the genus Struvea. 279 
branches are united by terminal organs of attachment precisely 
the same as the tenacula of S. delicatula . The branching 
takes place oppositely, and in one plane, but as the branches 
are mostly free they become more or less irregularly arranged 
when dried (Fig. 8 b). 
S . delicatula often grows in tufts with the fronds attached to 
one another by some of the pinnules of one adhering to the 
other frond by their tenacula. In one of the erect forms the 
end of a branch has attached itself by a tenaculum to a small 
piece of shell, which had fallen on the top of the tuft. 
The attachment of the branchlets must be very firm, be- 
cause., when two pinnules are torn apart, the tenaculum of the 
one sometimes tears off the outer layers of the wall of the 
other. Prolification of filaments sometimes occurs in S. deli - 
catida , as seen in Fig. 6 d> where the old filament must have 
broken off and a transverse wall helped in the formation of 
a new filament. 
We have been unable to find any traces of reproductive 
organs in any of the species of Struvea . In S. plumosa Kiitzing 
observed in one of the filaments 1 some dark green granular 
spherical bodies which he calls ‘ Keimzellen (?).’ They may 
be reproductive bodies, of some kind, but they remind one of 
the often spherical masses into which the protoplasm and 
chlorophyll of a cell of Cladophora frequently resolve them- 
selves when the wall has been injured and the turgidity 
destroyed. 
Until the reproduction of Struvea has been discovered its 
systematic position must remain doubtful. It is indissolubly 
linked with Chamaedoris and Apjohnia , and the evidence before 
us seems to point to this group as occupying a position among 
Siphoneae (sensu Agardh) near to Valonia, but connecting this 
series of forms with other green algae, such as Cladophora and 
Spongocladia. 
1 Tab. Phyc., Bd. vi. Tab. 90 f. 
