OF SOUTH AUSTRALIA. 
83 
to 600 in each sporangium, whose active motion has been observed. 
Apparently nothing more is known of them. The genus,, of which there is 
only the one species, seems to share certain characters of the Durvilleaceae 
and Laminariaceae. It is quite unique. 
SPLACHNIDIUM Greville. 
Splachnidium rugosum (L.) Greville. 
Attachment a small conical disc. Fronds one or several from the same 
base, cylindrical, truncate at the apex, bearing similar branches on all sides. 
Very slimy. Colour pale-green changing to brown when adult. Total 
height 10 to 20 cm. It grows on flat reefs adjacent to deeper water, and 
themselves overflowed at high tide. 
Victoria, Tasmania, New South Wales as far as Newcastle, New Zealand. 
It will probably be found on the coast of South Australia adjacent to 
Victoria. 
Order TETRASPORINAE 
Olive-brown plants, of moderate size, with thin flat membranaceous 
fronds, never fleshy or cartilaginous. The cells of the thallus are super- 
imposed in layers. They are mostly rectangular, easily adjusted in 
longitudinal and transverse rows. The outer cells are deeply coloured, 
rich in chromatophores and smaller; the inner cells are colourless and 
larger. The reproductive cells are superficial, scattered over the surface 
or grouped together in sori. 
Non-sexual and sexual plants are distinct. The non-sexual propagating 
cells usually divide into four, and have hence received the same name as 
the tetraspores which are characteristic of the Rhodophyceae. No 
observation has been made of the process of fertilization, but in the sexual 
plants there occur sori of small cells and of large cells, which have been 
tentatively designated antheridia and oogonia respectively. All the cells 
of the tetraspores and of the antheridia and oogonia are immobile, totally 
destitute of cilia. 
There is but one Family, Dictyotaceae. 
Family DICTYOTACEAE. 
The characters are those of the Order. 
KEY TO THE GENERA. 
a. Fronds flabellate, zoned with conspicuous lines 
of innovation. 
b. No independent tufts of paranemata on the 
frond. 
