446 BULLETIN OF THE BUREAU OF FISHERIES. 
Fairly abundant on Petalonia fascia, from Fort Macon jetty, April, 1908 and 1909, and fairly 
abundant on Nitophyllum medium, Bogue Beach, summer and autumn, Beaufort, N. C. 
‘This species was not found on Petalonia in December, 1908, nor January, 1909, was barely evident 
in February and March, and reached full development in April. 
The specimens on Nitophyllum have not been observed in a mature condition, but seem to agree 
closely with this species. , 
This is the only species forming a disk on the surface of other plants which has been observed here. 
As, however, several members of the Ectocarpacee have this form and may be found in this region, 
determinations should not be based on this character alone. 
Genus 2. Castagnea Derbes and Solier. 
Castagnea, Derbes and Solier, 1856, p. 56. 
Frond cylindrical, composed of an axis and peripheral radiating filaments with a 
stiffening, inconspicuous jelly; axis solid or tubular, composed of cylindrical, oblong 
cells joined into filaments tightly bound together by mucilage, forming almost a paren- 
chymatous structure; the peripheral filaments of rotund cells, going out from the axis, 
approximate and fasciculate, the sterile branches rather simple, enfolding the sporangia, 
the fertile branches thrusting out externally shorter subsecund branches below their 
apices; ‘‘plurilocular sporangia’ formed from the transformation of the upper (outer) 
segments of the assimilating filaments; ‘“‘unilocular sporangia’ produced as lateral 
offshoots from the base of assimilating filaments. 
About six species, North Atlantic Ocean, Mediterranean. 
The proper name for this genus is a matter of considerable doubt. But, as the 
author has had no opportunity for obtaining facts bearing on the question, it has seemed 
proper to follow the usage that is most current, even though further study should show 
that this name must be replaced by an earlier one. 
Castagnea zostere (Mohr) Thuret. Pl. LXX XVII, fig. 1. 
Rivularia zostere, Mohr, 1810, p. 367. 
Castagnea zostere, Thuret, in Le Jolis, 1863, p. 85. 
Castagnea zostere, Bérgesen, 1914, p. 184 (28), f. 144-145. 
(Not Castagnea zostere, Farlow, 1882, p. 86, pl. 7, f. 2.) 
(Not A. A. B. Ex. No. 162.) 
P. B.-A. Nos. 481, 1879 (Castagnea mediterranea). 
Frond filiform, cylindrical, somewhat inflated, attached by a small basal disk, 7 to 20 cm. tall; 
branching sparse or fairly abundant, alternate and irregular, branches arising almost horizontally, short 
or elongated and ascending, sometimes irregularly divided at apices, tapering toward the base and apex; 
structure tubular, the central cavity being bordered by longitudinal filaments tightly bound together 
with mucilage, nearly all the cells of the outer filaments of this central tube giving off several short, 
lateral, assimilating filaments and an occasional hair, growth of the longitudinal filaments intercalary; 
“unilocular sporangia’ oblong-ovate, arising from near the base of the assimilating filaments, “ pluri- 
locular sporangia’ conical or irregular in shape, sometimes branched, arising from the apices of the 
assimilating filaments, “unilocular’’ and “ plurilocular’’ sporangia occurring on the same plants; texture 
soft and rather gelatinous, the surface rough like the pile of velvet; color dark brown. 
Atlantic coast of North America and Europe. 
Fairly abundant on Bogue Beach, Beaufort, N. C., April 20, 1908; not found any other day. 
The identity of this species has been, and still is, the source of much confusion. Harvey (1852) gives 
a species under the name Mesogloia zostere Aresch; Farlow (1882) uses the name Castagnea zostere 
(Mohr) Thur., giving as synonyms, among others, Myriocladia zostere Ag. and Mesogloia zostere Aresch.; 
De Toni (1895) does not give Castagnea zostere, but recognizes two species (1) Myriocladia zostere J. Ag., 
giving as a synonym, among others, Mesogloia zostere Aresch., Exs. No. 67, Tab. VIII, f. 1, a and 6, and 
(2) Eudesme virescens (Carm.) J. Ag., giving as synonyms Mesogloia zostere Aresch., Alg. Scand. exs. 
No. 67, Linckia zostere Lyngb. and Aegira zostere Fries. Further study is needed to determine how 
many species are included here and to what genera these should be referred. 
