286 KJELLMAN, THE ALG^*: OF THE ARCTIC SEA. 



Habitat. The present species grows litoral, on exposed coasts, forming in com- 

 pany with Calothrix scopidoruin 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 tlie 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 Murnian Sea: the west coast of Novaya Zemlya local and scarce. 



Chsetophora pellicula nob. 



Cli. crustam membranaceam, 200 — 300 j.i. ciassara, e viride flavescentern formans, crusta c filis repeiitibus 

 deuse coiifertis, fila adscendentia phis minus ramosa, pilifera, rauco ubeviore cohibita emittentibus; cellulis vege- 

 tativis forma varia, 10 — 20 /.i. longis,! 6 — 10 /.t. crassis, membrana crassa; cellulis zoosporigenis subcylindricis, 

 15 — 20 /<. longis, 8 — 12 /.t. crassis. Tab. 31, lig. 4 — 7. 



Description. This alga forms a thin slimy membrane 200 — 300 jn. in thickness 

 of a light greeu or yellowish green colour. This membrane is composed of branching 

 cell-rows imbedded in sliine, the leading axes and some secondary axes of Avhich are 

 densely conipressed and horizontally expanded on the substratiim; 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 decurabent cell-rows are unilateral, those of 

 the rising ones issue from many sides (lig. 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 tive-angular in optical 

 longitudinal section, 5 — 10 ,«. thick by 10 — 12 ,«. long. Their membrane is thick, the 

 endochrome abundant. The zoosporogenic cells are cylindrical, somewhat bulging, 15 

 — 20 n. long, 8 — 12 ,«. thick. The opening is about in the middle of the longer wall 

 (% 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. 7naritima, but it dififers 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 Calothrix Harveyi. Spe- 

 cimens collected at the beginning of September bore scarce zoosporangia. 



Locality: The Norwegian Polar Sea: Finmarken at Talvik. 



