347 
longiores instructe« (Sp. g. 0. II p. 47). In the existing figures of this species, how- 
ever, the pectinate branching is only shown in one pinna in BorGEsEeN's fig. 56 b 
(Mar. Alg. Fær.), and it is evidently a rare occurrence, as also stated by J. Acarpn, 
while in our specimen it is to be found on all the branches. This may possibly 
be due to the young age of the plant. 
A similar seriate branching occurs in Phlebothamnion spinosum Kütz. (Tab. 
phye. 11 tab. 98), but only dispores are shown in Kürzıng’s figure, there is not so 
great a number of seriate pinnulæ, and the primary axis is corticated (comp. Sp. 
Alg. p. 653). Call. spinosum is, by the way, recorded by J. AGARDH under species in- 
quirendæ. In Phlebothamnion Gailloni Kütz. (Tab. phyc. 11 tab. 98 II) two seriate 
pinnulæ on the upper side of the pinnæ are shown in two pinnæ in the quoted 
figure, but this species seems to differ more by its fasciculate-corymbose bran- 
ching. 
As only a very small specimen is present it remains undecided, whether the 
main axis is corticated and whether the described branching is characteristic also 
of the adult plants. 
Locality. Ke: fJ 31/, miles W. by N. of Fladens light-ship. 30 meters, Oct. 
Seirospora Harvey. 
1. Seirospora Griffithsiana Harv. 
Harvey, Phye. Brit. Vol. I plate 21, 1846; Kützing, Tab. phyc. Bd. 12, Taf. 17, 1862; Schmitz, Die Gat- 
tung Microthamnion J. Ag. (= Seirospora Harv.), Ber. deut. bot. Ges. Bd. 11, 1893, p. 277; Jos. 
Schiller, 1913, p. 207; Oltmanns, Morph. I, 1904, p. 667; L. Kolderup Rosenvinge, 1920, p. 32. 
Callithamnion versicolor f, seirospermum Harv. in Hooker’s Journ. of Botany Vol. I, 1834, p. 302. 
Callithamnion seirospermum Griffiths, Harvey Manual 1841, p. 113; Areschoug, 1850, p. 108, Tab. IV G: 
J. Agardh, 1851, p. 42; Bornet et Thuret, Notes algol. fasc. I, 1876, p. XIV; Thuret et Bornet, 
Etudes phyc., 1878, p. 70. 
Pecilothamnion seirospermum Nägeli, 1861, p. 364, Fig. 13. 
The ramification of this species which somewhat reminds one of Callithamnion 
corymbosum to which it has also been referred, has been described by NAGELI in 1861 
and recently treated at large in my paper (1920) to which the reader may here be 
referred for more details. The main axes are vigorous, in their lower part covered by 
a well developed cortex composed of downward growing filaments produced in a 
number of three from the basal cell of each branch. The branches are almost always 
arranged in a spiral with a divergence varying between {/; and !/;, most frequently 
between !/, and 1/3. The spiral arrangement, however, does not begin at the very 
base of the branches, but the first branches are usually biseriate and arranged in 
a transversal plane, and the first joint (or 1 to 3 joints) is as a rule branchless. 
In all the specimens examined from Frederikshayn and Tonneberg Banke the spiral 
turned to the left. On the other hand, in a specimen from Herthas Flak only 4 of 
16 examined shoots had a spiral turning to the left; in 9 it turned to the right, one 
