456 
PACIFIC SCIENCE, VoL VIII, October, 1954 
LOCAL DISTRIBUTION: Epiphytic, 1-2 cm. 
tall, on Amphiroa, Sta. 1 (11131). 
Inasmuch as the name Polysiphonia snyderae 
is invalid for want of a Latin diagnosis, and 
since Hollenberg states that specimens labeled 
P. tongatensis from the Eriendly Islands, So- 
ciety Islands, and Hawaii in the New York 
Botanical Garden "are very close to if not 
identical with P. snyderae^' it seems best to 
refer the present specimens to the older name. 
My plants, although rather small, are in 
agreement with Kiitzing’s figure, which, how- 
ever, lacks several important details such as 
scar cells and the nature of the base. 
The epiphytic habit, attachment by uni- 
cellular rhizoids, the long segments, abundant 
trichoblasts, regularly placed scar cells in one- 
quarter divergence on each segment, and the 
branches replacing trichoblasts are distinctive 
characters. 
Polysiphonia coacta Tseng 1944^: 71, pi. 
2 (Hong Kong) 
Fig. 60g, h 
LOCAL DISTRIBUTION: Forming small tufted 
colonies 6-10 mm. high, Sta. 1 (11077, 
11310); Sta. 8 (11259). 
These three collections represent a short, 
saxicolous, quadrisiphonous species of small 
diameter (50-150 \x) with segments mostly 
shorter than broad, bearing scar cells in a 
regular one-quarter divergence spiral, and pro- 
ducing abundant connecting rhizoids. In all 
these characters they agree with Tseng’s P. 
coacta described from sand-covered intertidal 
rocks at Hong Kong. The type is up to 2 cm. 
tall. 
A collection from Sta. 10 (11329) is similar 
to the above specimens in size, habit, and 
structure, but differs in the irregular arrange- 
ment of the trichoblasts and scar cells, partly 
at intervals of one segment and partly at two 
(Fig. 60/). It probably represents a distinct, 
undescribed species, but is referred here as a 
close relative awaiting the more critical studies 
of a monographer of Polysiphonia. 
Acanthophora spicifera (Vahl) B0rgesen 
1910: 201, figs. 18, 19. Fucus spici ferns Ydhl 
1799: 44 (Virgin Islands) 
Fig. 61^, b 
LOCAL DISTRIBUTION: Loosely ramified, to 
20 cm. long, on shells and rocks, Sta. 4 
(11191) ; in drift, Sta. 3 (11094) ; on rocks, Sta. 
10 (11344). 
Key to the Species of Laurencia 
1. Thalli prominently flattened 
. L. parvipapillata 
Thalli cylindrical to only slightly com- 
pressed 2 
2. Surface cells radially elongated, in transec- 
tion arranged like a palisade 3 
Surface cells not radially elongated or ar- 
ranged like a palisade 4 
3. Axes + — percurrent, densely covered 
with short, turbinate branchlets 
L. papillosa 
Axes not percurrent; ultimate short branch- 
lets not very dense, not turbinate 
L. paniculata 
4. Thalli very small or slender, the axes and 
branches mostly 500 /x or less in diameter 
6 
Thalli not so small or slender, the axes 
and branches mostly over 800 fx in di- 
ameter 5 
5. Axes + — percurrent 
L. obtusa var. densa 
Axes not percurrent . L. corymbosa, prox. 
6. Thallus articulate here and there by an- 
nular scars .L. articulata, prox. 
Thallus not articulate 7 
7. Thalli creeping on coral, loose. ........ 
L. pygmaea 
Thalli erect, densely tufted or turf-like . . 8 
