538 
PACIFIC SCIENCE, VoL XXII, October 1968 
or syntypes and many glucose slide mounts of 
various species will be stored at the University 
of Hawaii. 
Acknowledgments 
This study was made possible through the 
support of Research Grant GB-2735 of the U. S. 
National Science Foundation. The writer is also 
grateful for the use of facilities of the Botany 
department of the University of Hawaii, where 
the major part of the work was done, and for 
the services of the departmental artist. The work 
was greatly facilitated by access to the excellent 
phycological library of Dr. Maxwell S. Doty of 
the Department of Botany of the University of 
Hawaii. 
The material collected by C. R. Long was 
collected under the auspices of the Pacific Ocean 
Biological Survey Program conducted by the 
Division of Birds, Smithsonian Institution. 
Herposiphonia arcuata sp. nov. 
Fig. 5 
Densely branched algae, forming extensive 
patches mostly on other algae; main axes com- 
monly growing free from the substratum, and 
most of the indeterminate branches developing 
into laterals of varying lengths; indeterminate 
branches 140-1 90p in diameter, with segments 
1.0— 1.5 diameters long; determinate branches 
morphologically erect, arising mostly at intervals 
of 3 segments, alternately on either flank, fol- 
lowed by an indeterminate branch on the same 
side, but more lateral in position; mostly 1 but 
frequently 2 or more nodes without a branch 
occurring between an indeterminate branch and 
the next distal determinate branch; determinate 
branches composed of 10-1 2- (20) segments, 
1. 0- 2.0 diameters long, strongly arched distally, 
and mostly remaining slightly arched when ma- 
ture; pericentral cells mostly 10, slightly smaller 
than the central cells ; chromatophores non- 
zonate; walls brownish, relatively firm; tricho- 
blasts usually 2-3 per determinate branch, usu- 
ally poorly developed, but sometimes up to 1.7 
mm long, with 4—6 dichotomies; tetrasporangia 
60-7 5 p in diameter, in series of 4-6 in the mid- 
dle or terminal parts of the branches ; cystocarps 
ovate to globular, to 300p in diameter, arising 
terminally on the 6th to 9th segment, the branch 
growing beyond the developing cystocarp 8-9- 
(15) segments and bearing in succession 5 or 
more trichoblasts spirally arranged ; sperma- 
tangial stichidia l60-175p long, 50-65jx broad, 
mostly one per segment in spiral sequence on 
8-12 short terminal segments, each arising as a 
primary fork of a trichoblast, and terminating 
in a sterile tip of 1-2 short cells, quickly decidu- 
ous. 
Algae ramosissimae, maculas amplas in saxis et in 
algis aliis formantes; partes distales ramorum prin- 
cipalium a substrato plerumque discretae crescentes; 
plerique ramuli indeterminati in ramulos laterales 
longitudine variantes evolventes; ordinatis ramifi- 
cationis unum nodum sine ramis et unicum ramum 
determinatum dorsilateralem inter ramos indetermi- 
natos plerumque praebens; rami determinati e 10-12 
segmentis 1.0-1. 5 plo longioribus quam latis, versus 
extremitatem distalem rami fertilis valde arcuatis 
plerumque compositi; cellulae pericentrales plerumque 
10; chromatophora non zonata; trichoblastae plerum- 
que duae, usque ad 1.3 mm long., 4-5 dichotomias 
habentes; tetrasporangia 60-75p diam., 4-6 continua; 
cystocarpi ova ti ad fere globularos, ad 300p diam., 
terminaliter orientes, ramo 8-10 segmenta ultra cysto- 
carpum evolventem formante; stichidia spermatangialia 
160-1 75 p X 5 0-65 p, cacumen sterile, ex una ad duas 
cellulas breves constans, habentia, saepissime unum 
spermatangium in omni segmento in spira in 8-10 
segmentis terminalibus brevibus, omne spermatangium 
ut furca primaria trichoblastae oriens, mox, autem, 
deciduum. 
TYPE collection: D. 19611, tetrasporic, 
cystocarpic, spermatangial, awash at Kailua, 
Oahu, Hawaii, legit M. S. Doty and H. B. S. 
Womersley, Jan. 21, 1962. It is represented by 
two glucose slide mounts and considerable 
fluid-preserved material. 
ADDITIONAL COLLECTIONS EXAMINED: HA- 
WAIIAN islands: — D. 13019, on reef, Koloa, 
Oahu, Oct. 30, 1955; D. 13039A, cystocarpic, 
on Griffithsia sp., and D. 13051, on Sargassum 
sp., both awash, Kailua Beach Park, Oahu, Nov. 
27, 1955; D. 17110, cystocarpic, on Sargassum 
sp., near the Natatorium, Waikiki, Oahu, Nov. 
20, 1958; D. 20050.1, tetrasporic, spermatan- 
gial, on other algae, wave-battered shore, Laie, 
Oahu, legit R. Tsuda, R. Buggeln, and G. 
Trono, May 5, 1963; D. 20224, tetrasporic, 
awash, Kailua Beach Park, Oahu, Nov. 14, 
1965 ; an unnumbered collection by M. Kaji- 
mura, tetrasporic, on Sargassum sp., Sans Souci 
