Polysiphonia of the Tropical Pacific, I — Hollenberg 
73 
diameter; tetrasporangia 30-40p in diameter, 
in short series not much distending the seg- 
ments ; cystocarps globular, to 260p in diameter ; 
spermatangial branches 175-200p X 45-5 Op 
arising as a primary fork of a trichoblast, usually 
with 1-2 short cells forming a sterile tip. 
Algae minutae, epiphyticae, ramos prostratos, af- 
fixes per rhizoidea unicellularia, cacuminibus digi- 
talis praedita, ab extreme proximali cellularum peri- 
centralium separata, interdum, autem, aggregationem 
rhizoideorum, ramo prostrate carente, habentes; 4 
cellulae peri centrales excorticatae tangentialiter sub- 
complanatae, segmentis plerumque brevioribus quam 
lata, interdum, autem, 1. 5-2.0 longiores quam lata, 
et parietes stratifactos, usque ad 15p crass, in parti- 
bus vetustioribus brunneolos, habentes; rami erecti, 
origine ut videtur cicatrigeni, 125— 245pi diam. 4-6 
mm long., paucos ramos laterales habentes; rami 
laterales in associatione cum trichoblastis, aut cicatri- 
gene, intervallis 20-30 vel plurium segmentorum 
enascentes, trichoblastae tenuissimae ad 400 (500)p, 
long., 8-1 2 p diam. ad basim, 3-4 furcas habentes, 
una in unoquoque segmento in spira enascente, rela- 
tive persistantes, effusae, autem, cellulas-cicatrices 
parvas 7-8p diam. relinquentes ; tetrasporangia 30- 
40p diam., in serie brevi, segmenta paulum disten- 
dentia; cystocarpi globosi, ad 260p diam., rami sper- 
matangiales 175-200p X 40-50p ut furca primaria 
trichoblastae enascentes, 1-2 cellulas breves, cacumen 
sterile formantes, plerumque habentes. 
type: D. 19116AI1, cystocarpic, attached to 
a species of Galaxaura, dredged from 15 fa, 
Pokai Bay, Oahu, Hawaii, Aug. 1, 1959. It 
is represented by a glucose microslide mount. 
ADDITIONAL COLLECTIONS (all mostly sub- 
littoral in habitat): D. 19H6J2, spermatangial, 
on Gracilaria sp. dredged 15 fa, Pokai Bay, 
Oahu, Hawaii, Aug. 1, 1959; D. 19135L1, 
tetrasporic, cystocarpic, on Sargassmn sp., D. 
19135J2, on Padina sp., D. 19135W3, all 
dredged 26 fa, in front of the river, Waialua, 
Oahu, Hawaii, Aug. 2, 1959; D. 19143S1, 
spermatangial, on Amansia sp., dredged 15-20 
fa, Ilio Pt., Molokai, Hawaii, Aug. 7, 1959. 
This species is closest to P. flaccidissima in 
the origin of branches in relation to tricho- 
blasts, and in its small size and delicate nature. 
From P. flaccidissima it differs in the relatively 
persistent trichoblasts, in the brownish color of 
the walls, and in the less frequent branches, 
terminal portions of erect branches having as 
many as 80 segments without a lateral branch. 
Polysiphonia pseudovillum sp. nov. 
Fig. 3 C 
Plants chiefly prostrate with creeping fila- 
ments to 60p in diameter, composed of seg- 
ments 1.0-1. 5 diameters long, attached by 
frequent unicellular rhizoids which are cut off 
from the proximal end of the pericentral cells 
by a cross-wall, and with a broad base in con- 
tact with the bearing cell although only a nar- 
row pit-connection, and which may have digitate 
tips; erect branches arising cicatrigenously at 
frequent intervals, to 1 or up to 2.7 mm high 
and 40-60p in diameter, with segments about 
1.5 diameters long, with slight constrictions at 
the nodes, and only occasionally with one or 
more laterals arising cicatrigenously in a pseudo- 
dichotomous manner; pericentral cells 4, ecorti- 
cate and with a central cell scarcely half the 
diameter of the pericentral cells; walls hyaline, 
5-8p thick; trichoblasts to 1 mm long, with 
mostly 4 dichotomies and very slender tips, and 
with a basal cell to 3 5 Op long and 18p in 
diameter, arising at irregular intervals in part 
but mostly one per segment in J spiral sequence 
in terminal parts of erect branches, tardily 
deciduous ; scar-cells mostly one per segment on 
both prostrate and erect branches, but some- 
times at intervals of two segments; tetrasporan- 
gia (immature) in short spiral series near the 
tips of branches; cystocarps ovoid to slightly 
urceolate, 15 Op broad and slightly longer than 
broad; spermatangial branches (only one seen) 
oblong, 220p X 58p, arising probably as a 
primary branch of a trichoblast. 
Plantae praecipue prostratae, filamenta repentia ad 
60p diam., e segmentis 1-15 plo longioribus quam 
lata composita, affixa per rhizoidea unicellularia fre- 
quentia, per dissepimentum ab extreme proximali 
cellularum pericentralium separata, habentes; rami 
erecti intervallis frequentibus cicatrigene enascentes, 
plerumque 1 mm alt. aut paululo altiores, segmentis 
ca. 1.5 plo longioribus quam lata, ramis inter seg- 
menta aliquantulum constrictis, parcis ramis cicatri- 
gene enascentibus; cellulae peri centrales 4, ecorticatae, 
cellula centrali multo minore quam cellulae peri- 
centrales; trichoblastae ad 1 mm long., ca. 4 dichoto- 
mias necnon cellulam basalem ad 350|X long., 18p, 
diam., una in unoquoque segmento in I spira in parti- 
bus terminalibus ramorum erectorum maxima ex parte 
oriente, habentes. Cellulae-cicatrices plerumque una 
in unoquoque segmento in maris et erectis et pro- 
stratis, interdum intervallis 2 segmentorum; tetra- 
sporangia in serie brevi spirali; cystocarpi aliquan- 
