414 
PACIFIC SCIENCE, VoL VIII, October, 1954 
doubtedly this character is more conspicuous 
against the translucent membrane of Chae- 
tomorpha than against the dark surface tissue 
of Sargassum. The chromatophores are dis- 
tinctly parietal. 
Acrochaetium occidentale B0rgesen 1915: 
44, figs. 42, 43 (Virgin Islands) 
Fig. 25^, c 
LOCAL distribution: Forming a silky pile 
about 1.5 mm. long on Liagora at Sta. 1 
( 11121 ). 
This material is identical with the West 
Indian species except that only monospores 
have been detected thus far. 
Acrochaetium subseriatum B^rgesen 
1932^: 118, figs. 6, 7 (South India); B^r- 
gesen 1942: 15, fig. 6 
Kg- 25/. g 
LOCAL DISTRIBUTION: Forming small tufts 
1.5-2 (or sometimes to 6) mm. high on 
Pterocladia, Sta. 6 (11221). 
My material is apparently more luxuriantly 
developed than B0rgesen’s scant original 
specimens from the Gulf of Mannar, or those 
from Mauritius, but they are otherwise in 
full agreement. The main axes are about 8 ju 
in diameter and the monospores 12-13 m long. 
Acrochaetium gracile B^rgesen 1915: 26, 
figs. 19, 20 (Virgin Islands) 
Fig. 25/>, i 
LOCAL DISTRIBUTION: Forming a fine fur 
about 0.9-1. 2 mm. long on the surface of 
old Diplanthera leaves in drift, Sta. 3 (11105); 
in small tufts 0.6-0. 7 mm. high on Gelidiella, 
Sta. 4 (11341a). 
The material under 11341a is in close agree- 
ment with B0rgesen’s account of the West 
Indian plant. That under 11105 is about 30 
per cent larger in all dimensions. 
Acrochaetium robustum B0rgesen 1915: 
40, figs. 38-40 (Virgin Islands); B0rgesen 
1920: 449, hg. 418; Tseng 1945: 158, pi. 
1, figs. 2-4; Abbott 1947: 203, hg. 4 
Fig. 25/, k 
LOCAL DISTRIBUTION: Abundantly epiphytic 
on Sargassum, forming a fine, reddish, velvet- 
like covering over nearly all parts of old 
fronds, Sta. 3 (11174); Sta. 10 (11347). 
These plants are up to 2 mm. high. The 
filaments are mostly 6-10 /t in diameter. A. 
sargassicola B0rgesen (1932^?: 115, figs. 3-5) 
from Bombay, India, does not seem to be 
distinct from A. robustum. See also Papenfuss 
(1945: 317) as to A. lauterhachii (Schmitz & 
Heydrich) Hamel. 
Falkenbergia hillebrandii (Bornet) Falken- 
berg == sporophyte generation of Aspara- 
gopsis taxtformts (Delile) Collins and Hervey. 
Feldmann and Feldmann 1942: 89; Dawson 
1953: 57. Polysiphonia hillebrandii Bornet, 
in Ardissone 1883: 376 (Italy) 
Fig. 25/ 
LOCAL DISTRIBUTION: Epiphytic in small, 
loose tufts and scattered filaments on algae, 
Sta. 10 (11324). 
No specimens of Asparagopsis have yet been 
found in the Nha Trang area, and the specific 
identity of this sporophyte generation of a 
species of that genus is therefore in doubt. 
It is tentatively referred here to the wide- 
spread, tropical A. taxiformis. 
Dermonema frappieri (Mont. & Millard.) 
B0rgesen 1942: 42, fig. 21. Gymnophloea 
gmci/h Martens 1866: 146. Cladosiph on frap- 
pieri Montagne and Millardet 1862: 20, pi. 
26, fig. 1 (Reunion Island). Tseng 1945: 
159, pk 1, figs. 5, 6 (as Dermonema gracilis) 
Fig. 2^m 
LOCAL DISTRIBUTION: Growing in dense, 
erect tufts 4-5 cm. high, Sta. 8 (11272). 
The illustration of the type given by Bpr- 
gesen is in close agreement with the Nha 
Trang specimens. His notes from Jadin on 
the habitat in Mauritius, and those of Tseng 
