286 KJELLMAN, THE ALG OF THE ARCTIC SEA. 
Hatitat. The present species grows litoral, on exposed coasts, forming in com- 
pany with Calothrix scopulorum a thin layer on stones and rocks above low-water mark. 
It is gregarious and occurs sometimes in considerable masses. As yet found only 
sterile. 
Geogr. Distrib. Known only from the Polar Sea north of the Atlantic. Its nor- 
thernmost point is Fairhaven on the north-west coast of Spitzbergen. Lat. N. 79° 49’. 
Localities: The Greenland Sea: the north-west and west coast of Spitzbergen 
local, but at certain places abundant. 
The Murman Sea: the west coast of Novaya Zemlya local and scarce. 
Chetophora pellicula nob. 
Ch. crustam membranaceam, 200—300 wu. crassam, e viride flavescentem formans, crusta e filis repentibus 
dense confertis, fila adscendentia plus minus ramosa, pilifera, muco uberiore cohibita emittentibus; cellulis vege- 
tativis forma varia, 10—20 w. longis,) 5—10 «. crassis, membrana crassa; cellulis zoosporigenis subcylindricis, 
15—20 we. longis, 8—12 w. crassis. Tab. 31, fig. 4—7. 
Description. This alga forms a thin slimy membrane 200—300 wu. in thickness 
of a light green or yellowish green colour. This membrane is composed of branching 
cell-rows imbedded in slime, the leading axes and some secondary axes of which are 
densely compressed and horizontally expanded on the substratum; other secondary axes 
rise upwards, issuing at a greater or smaller angle. The branching of the cell-rows varies 
considerably, being sometimes very scarce, sometimes so profuse that almost every cell 
puts forth a branch. The branches of the decumbent cell-rows are unilateral, those of 
the rising ones issue from many sides (fig. 4—5). The hairs are long and rather nume- 
rous. The vegetative cells are very variable in form, sometimes almost spherical, some- 
times square, rectangular, elliptic, irregularly three-, four-, or five-angular in optical 
longitudinal section, 5—10 #. thick by 10—12 mw. long. Their membrane is thick, the 
endochrome abundant. The zoosporogenic cells are cylindrical, somewhat bulging, 15 
—20 uw. long, 8—12 u. thick. The opening is about in the middle of the longer wall 
Gig. 7); 
Besides by zoospores, the present species is propagated by resting cells, produced 
by the transformation of vegetative cells. These rest either in the parent plant or in 
other plants together with which it occurs. Thus cells of that kind were found very 
numerous in the frond of Lithoderma lignicola growing on Ch. pellicula. After becoming 
free, they increase considerably in size, their contents are augmented and their mem- 
brane thickened. Their further development is unknown to me. 
This species is closely related to Ch. maritima, but it differs essentially from it 
in branching and by the crustaceous form of the frond. 
Habitat. It has been found in sheltered localities within the litoral zone, on old 
decaying wood, growing together with Lithoderma lignicola and Calothria Harveyt. Spe- 
cimens collected at the beginning of September bore scarce zoosporangia. 
Locality: The Norwegian Polar Sea: Finmarken at Talvik. 
