462 
much branched, forming small fascicles of stichidia each containing two series of 
sporangia. 
O. dentata is perennial; it attains a length of up to 20 cm, thus in the most 
southern locality recorded in the Sound. It has only been met with in the months 
of April to September. The new shoots must arise in winter; in spring they are of 
a fresh red colour in contrast to the shoots of the foregoing year. The organs of 
fructification must develop in winter. According to ARESCHOUG the species is fructi- 
ferous in winter (Dec. to March) at the west coast of Sweden, and that is probably 
also the case in the Danish waters, but tetraspore-bearing specimens have been met 
with as late as May, and cystocarp-bearing ones were collected in April and even in June 
(Store Belt). On the other hand, specimens were found in May with adventitious 
shoots having shed the outer fructiferous part. 
The species is confined to the waters with high salinity and slightly varying 
temperature; it has therefore principally been met with in the deeper parts of the 
eastern Kattegat in 15 meters’ depth and deeper. In slighter depth it has only been 
collected in one place in the northern Kattegat on the north side of Hirsholmene. 
In the Great Belt it has only been found in one place in 19 meters’ depth, and in 
the Sound south of Helsingör only in one place in 22,5 meters’ depth in the deep 
channel. It grows on stony or gravelly bottom and may be fixed to Litothamnia, 
barnacles or mollusks, has also been found on Fucus serratus and Polysiphonia elongata. 
Localities. Kn: East of Tyskerens Rev, Hirsholmene, c. 11 m; VX, Böchers Banke, 29 m. — 
Ke: IL!, IM, ZE!, ZE?, ZF, IP, IQ, Dana St. 2922 (C. A. J.), Fladen, 15—30 m; Groves Flak, 24,5 m; 
IK, Lille Middelgrund, c. 18 m; RU, 26,5 m; IA, Store Middelgrund, 17 m. — Ks: Lysegrund (Lyngbye, 
Rhodomela dentata, Rariora codana, p. 225); near Hesselo (Lyngbye); off Isefjord, buoy at Gronne 
Revle in S. 3 miles, 15 m (Biolog. Station). — Sa: The Herbarium of the Bot. Mus. of Copenhagen 
contains a denudate specimen of Polysiphonia elongata bearing in Hornemann’s handwriting the follow- 
ing labelling: “hab. ad littus Hofmansgave saxis adnascens ded. Lyngbye”. This bears some small spec- 
imens of O. dentata, c. 1 cm long. — Sb: Off Refsnes, 19 m (C. H. Ostenfeld). — Su: Off Aalsgaarde 
(Th. Mortensen), off Hellebæk (Orsted); frequently cast ashore at Julebæk and Hellebæk; bM, south of 
Hveen, 22,5 m. 
General Remarks on the Morphology of the Danish Rhodomelaceæ. 
The following remarks deal particularly with the genus Polysiphonia which 
has been most thoroughly studied as to the morphology. Further information on 
the morphology of this interesting family must be sought in the quoted papers of 
FALKENBERG, KYLIN a. 0. 
1. The hair-shaped organs which were named leaves by NAGELI (1846) were 
repeatedly studied by various authors. I treated them in 1903 and gave them the 
name trichoblasts; they might also be named hair-leaves. Vegetative trichoblasts occur 
in all the Danish species of Rhodomelaceæ except Odonthalia and Heterosiphonia. 
In Polysiphonia they occur only in the erect shoots, not in the creeping ones. In 
this genus they are usually hyaline though provided with small colourless plastids. 
