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PACIFIC SCIENCE, Vol. IX, October, 1955 
above each dichotomy in the basal filaments, 
and C. pusilla usually has constrictions above 
the upper branch axils. It seems likely that 
the characters separating Pseudochlorodesmis 
from Chlorodesmis may be of subgeneric rather 
than generic order. 
Pseudocodium australasicum n. sp. 
Figs. 5, 6 
Thallus erect, subdichotomously or irreg- 
ularly branched, to 6 cm. high, branches 1-2 
mm. wide, compressed, branching partly 
(especially when young) in one plane, colour 
dark green. Holdfast small, of dense, colour- 
less filaments. Thallus composed of a medulla 
of longitudinal, branched, coenocytic fila- 
ments, 13-28 fj, thick, forming at the surface 
a cortical layer (12-27 /x wide) of short club- 
like branches, 4-7 /x wide, sub-palisade like; 
surface view of thallus showing ends of cor- 
tical branches, round to polygonal, 5-9 m 
across, adhering together. Growth apical, by 
numerous longitudinal medullary filaments, 
slenderer than normal medullary filaments. 
Filaments with numerous nuclei and small 
discoid chloroplasts, 1-2.5 m across. 
Thallus erectus, subdichotome aut irreg- 
ulariter ramosus, ad 6 cm. altus, rami 1-2 
mm. lati, compressi; rami partim in una plana, 
fusco-viridis. Filamenta medullaria ramosa, 
13-28 fi diam. Cortex 12-27 /x lata brevium, 
clavatorum ramorum (4-8 \j, diam.) 
type locality: Point Sinclair (east end of 
Great Australian Bight) South Australia; up- 
permost sublittoral on a relatively calm reef 
near the old jetty. 
type: AD (No. A 13,618, H. B. S. Worn- 
ersley, January 25, 1951). Isotypes distributed 
under this number. 
distribution: Known only from the type 
locality and from a drift specimen about 10 
miles east of Eucla, on the South Australian 
—Western Australian border (AD No. A 
19,239, February 3, 1954). 
P. australasicum is apparently a rare species. 
A small patch of a number of plants was 
found at Point Sinclair in January 1951, but 
this could not be located in February 1954. 
This is the second described species of 
Pseudocodium , the type being P. devriesii Weber 
van Bosse (1896: 209, pi. 1. See also Levring 
1938: 14, fig. 7, pi. 4, fig. 10) from South 
Africa. In general structure and method of 
growth P. australasicum agrees well with P. 
devriesii , but differs in its smaller size and the 
less well developed layer of cortical palisade- 
like branch ends. The formation of the cor- 
tical layer shows more affinity with Halimeda , 
as noted by Weber van Bosse and Levring 
for P. devriesii , than with Codium , to which 
it is considered allied by Gepp and Gepp 
(1911: 3). 
Order SIPHONOCLADALES 
Family SIPHONOCLADACEAE 
Cladophoropsis magnus n. sp. 
Fig. 7 
Thallus forming large tangled masses up 
to 50 cm. across and 7 cm. thick, with the 
Fig. 5. Pseudocodium australasicum n. sp. a. Longi- 
tudinal section of thallus (X 280); b, detail of a medul- 
lary filament forming short cortical branches, showing 
nuclei and chloroplasts (X 500); c, surface view of 
cortical filaments (X 500). 
