140 THE JOURNAL OF BOTANY 
A section of the tip of any fertile branch (fig. 12) shows that 
the tissues are quite mature right up to the apex, thus ae 
a great contrast with a sterile growing branch, owing to 
aiffarenae:: in appearance between young and mature cells ripe: 
described. The sporangia, which occur all over the surface of the 
plant, are unilocular, and are modified cells of the limiting layer ; 
first begins, as in the material available mature spor angie 
found on all parts of the plant. They are distinguishable in the 
earliest stage (fig. 13) as cells of the limiting layer which hav 
swollen a little and do not stain quite so deeply. They wonibace 
to grow until their shorter diameter is three or four times that of 
a cell of the limiting layer, and they are somewhat pear-shaped. 
Then the protoplasm ae ove a vacuolated (fig. 14); these 
vacuoles swell, and so: of the n together, so that they 
become rrepalaan in shape. After this t sie protoplasm increases in 
amount, thus rome a the vacuoles, at me e same time it 
ecomes marked out in a oe. areas; the eas are partly 
bounded by the hte and partly b $ ot: larger and more 
deeply-staining granules 15). Finally, fissures extend in- 
elve 
off to form spores (figs. 16 and 17). The method of dehiscence 
of the sporangia was not obi ed. 
It will be seen from the above that in the mature structure of 
the thallus Scytothamnus stands between Dictyossphonacee and 
Chordariacee, while in the position and structure of its sporangia 
; pat : t 
work has been done on the group that it is impossible to estimate 
the value of this character, or indeed of any character, in discuss- 
ing the systematic position of the plant. 
It has been thought for a long time that S. australis is iden- 
tical with the plant known as D. fasciculatus. The dried material 
of this species in the National Herbarium was examined, with the 
result that the type-specimen bearing the following label—‘ D. fas- 
eiculatus H.& H. Lord heckinnc’s Is., J. D. Hooker, Antaret. 
Exped. 1839-43,” was found to differ from S. australis in being 
quite hollow, and in the fact that the cjg oa cells, instead o 
forming radiating moniliform filaments, joined into a solid 
parenchyma of rounded cells, in fact the lant ad the structure of 
a true Dictyosyphon. The sporangia strongly resemble those of 
S. australis, but so also do those of other species of ss hig Hey 
Four other dried specimens—viz., D. f. wlatus Hook. = 
Eden Harbour, Magellan Straits; D. teemounins, Koooler S 
d, 1842, Lieut. A. Smith; D. fasciculatus, Falkland Is., J. D. 
Hooker; Desmarestia fasciculata, Campbell Island, No. 43, Dr. 
