2 y6 Murray and Boodle— A structural and 
must be the mouths of tubes which, by their repeated branch- 
ing, produce the whole of the rootlets. 
In addition to these usual organs of attachment, there are 
also remarkable structures of the kind at the bases of some of the 
filaments of the frond, which in shape resemble the sporangia 
of Botrydium (Fig. 3 h). They have evidently been produced 
by the formation of a small wart-like outgrowth from the base 
of a branch just above its basal wall. The outgrowth then grew 
downwards parallel to the filament, producing a neck-like pro- 
longation which curved inwards and came into contact with 
the surface of the filament below the transverse wall, and then 
threw out a fan-shaped mass of branched rootlets on the wall. 
These organs occur in the specimen examined at the point of 
origin of the frond, where the stalk divides into three filaments, 
each of which has two of these organs at its base (Fig. 3 g) ; 
there are three or four at each of the next two points of branch- 
ing of the midrib, and, at a point in the stalk where there 
is a transverse wall, five or six of these clamps connect the 
part of the stalk above the cross-wall with that below. 
Similar bodies were detected at the base of the frond of 
Dr. Piccone’s specimen, but nothing like them has been seen 
in the other species of Struvea. From the arrangement of 
contents these bodies do not seem to be cut off from the cavity 
of the filament which produces them. 
The frond of S', pidcherrima , as stated above, is supported 
by three main filaments. Its outline and dimensions cannot be 
determined, owing to the fragmentary nature of the specimen, 
but the probable shape is that given in Fig. 4 and the size 
would be about 10 inches in length by 6 to 7 inches in 
breadth. Each of the three filaments branches into four ; 
these remain simple for a short distance and pass into the 
frond, where they are traceable as veins, which in their turn 
produce veinlets, and the branching is repeated several times, 
so that, by the attachment of the ultimate branches to each 
other and to the veins, a very perfect network is formed (Fig. 
4 b). The veins and veinlets generally give off two or four 
branches just below their transverse walls, but here and there 
