444 
PACIFIC SCIENCE, VoL VIII, October, 1954 
ish pile 3-4 mm. high on the surface of coral 
dredged from 2-3 m., Sta. 2 (11366). 
This material is quite clearly of an un- 
described species apparently nearly related to 
Antith amnion antillanum B0rgesen (1917) 
which Nasr (1941) considers a variety of A. 
Iherminieri (Cr.) Born. Unfortunately my ma- 
terial was rather badly preserved and does not 
remain in suitable condition for description 
and deposition of a type. However, it is here 
illustrated and briefly characterized for the 
aid of future collectors. 
Like A. antillanum, this plant has creeping, 
verticillately branched, main filaments, part of 
the branches becoming transformed into rhiz- 
oids while others become erect and in turn 
alternately branched. The basal cells of the 
branches from the primary axes are usually 
much shorter than the others, as in A. an- 
tillanum, but no gland cells have been ob- 
served. The tetrasporangia and capitate an- 
theridial clusters are pedicellate as shown in 
the figures. The cystocarps consist of a gon- 
imoblast cluster surrounded by a dense in- 
volucre of incurved branchlets about 500 /i, 
long, somewhat as in Mesothamnion (B0rgesen 
1917: 214, fig. 200). 
Mesothamnion caribaeum B0rgesen 1917: 
208, figs. 194-200 (Virgin Islands) 
Fig. 54^, b 
LOCAL DISTRIBUTION: Forming small, dense, 
rounded tufts to 1 cm. high among other 
small algae at low levels, Sta. 8 (11262). 
It was surprising to find this Nha Trang 
material to be in such close accord with B0r- 
gesen’s account as to be referable with con- 
fidence to this West Indian species. Although 
my plants are somewhat smaller throughout 
than the type, they agree closely in habit, 
proportions, rhizoidal attachment, branching, 
and in tetrasporangial and antheridial char- 
acters. The antheridial structures are particu- 
larly striking. Cystocarps were not found. 
Callithamnion sp..^ 
Fig. 54^, ] 
Mixed with other minute algae growing on 
bits of debris dredged from 2-4 m. off Cau 
Da were a few small examples about 1 cm. 
high of what appears to be a species of Cal- 
lithamnion (11295). They consist of a per- 
current axis about 70 in diameter bearing 
very slender branches in a spiral arrangement. 
Reproductive organs suggesting large spher- 
ical monospores occur, each surrounded by a 
group of loosely encircling filaments. These 
spherical structures have dense, coarsely gran- 
ular contents and reach 150 ju in diameter. 
The present material is too scant for further 
elucidation. 
Wrangelia argus (Mont.) Montagne 1856: 
444; B0rgesen 1916: 116, figs. 125-126; 
Weber van Bosse 1921: 220. Griffithsia argus 
Montagne 1840^: 176, pi. 8, fig. 4 (Canary 
Islands) 5 ^^ 
LOCAL DISTRIBUTION: Forming soft, carpet- 
like patches on rocks at about -f 1 foot level, 
Sta. 1 (11084, 11113); Sta. 4 (11159). 
These small plants, mostly about 1 cm. 
high, are characteristic of this species which 
is now known from the tropical Atlantic, 
Pacific, and Indian oceans. 
Antheridia appear on some of the spec- 
imens. They are in spherical, capitate clusters 
in the same position and of about the same 
size as the tetrasporangia. 
Spyridia filamentosa (Wulf.) Harvey, in 
Hooker 1833: 337; Taylor 1928: 197, pi. 
28, figs. 14-18. Fums filamentosus Wulfen 
1803: 63 (Europe) 
Fig. 54/ 
LOCAL DISTRIBUTION: Growing on shells 
and debris as soft, loose clumps 10-13 cm. 
high, Sta. 4, 5 (11107, 11192). 
The determinate branchlets are tipped with 
a single spine. 
