filled with hypha-like filaments. The tricho- 
blasts are branched, in greater depths provided 
with feebly rose-coloured chromatophores. The 
frond may be 30 cm long or more. 
In the Baltic Sea around Moen (Bm) and 
around Bornholm (Bb), where the salinity is 
much feebler, the species occurs in a still 
slenderer form which at first I judged identical 
with f. expansa (Ag.) which J. Agardh first found 
at the coast of Blekinge. An examination of the 
original specimen of Hutchinia expansa Agardh 
in AGARDH’s herbarium in Lund showed me, 
however, that AGARDH’s species cannot be 
referred to P. elongata as its branches arise 
in the axils of the trichoblasts, but that it is 
a form of P. violacea. I have therefore given 
the here described form of P. elongata from 
the Baltic Sea the name f. baltica. The frond 
of this form is very slender, up to 20 cm long, 
and has an intense red colour. The joints are 
4—7 times as long as broad wbere the cortic- 
ation begins. The branches are not attenuated 
towards the base. The cortication often begins 
rather late and advances more slowly down- 
wards so that 
the pericentral 
SR; Fig: 96 cells do not be- 
Polysiphonia elongata f. baltica. A, upper end of 4 
shoot; trichoblasts with chromatophores. come entirely 
covered by the 
cortical cells. The main axis is only 140—280 w thick. 
The trichoblasts are unbranched or slightly branched 
with well developed, feebly rose-coloured chromato- 
phores; they are usually long kept. When adventitious 
shoots occur they may arise before the trichoblasts 
have been shed (fig. 364). This form is confined to 
localities with feeble salinity and rather feeble light 
(9—24,5 meters depth). Specimens from the deepest 
localities in the outer waters with high salinity may 
resemble f. baltica in some characters, but are so differ- | 
ent in other respects that they cannot be referred to Fig. 364. 
it. In the Limfjord, in depths of 7 to 10 meters, where Polusiphonia elongata f. baltica, from 
2 3 u ; à Flensborg Fjord. Secondary axillary 
the light is very feeble, owing to the very turbid water, shoot. 230 : 1. 
