o 



KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. 297 



burst at the top, expancl and become slit usually in their whole length. The segments 

 when fuUy grown are even 10 cm. long, sonietimes few in number, being then ovate 

 or elliptical, sometimes nuraerous, being then usually lanceolate or oblong, in both cases 

 often repeatedly and more or less deeply divided. The margin of the segments is 

 generally wavy or crisp; fig. 3 — 4. When the frond grows older, it either detaches 

 itself altogether from its substratum or else a number of segments are loosened that 

 aftervvards float on the surface of the water or lie loose on the bottom. These seg- 

 ments, after having become free, often increase considerably in size. There are to 

 be found pieces which have a length of 15 — 20 cm. by a breadth of about 10 cm. 

 When growing older the plant assumes a påle yellowish-green colour. It is loose and 

 slimy in consistency so that it adheres strongly to the paper in drying. The lowest 

 part of the frond nearest the callus is composed of claviform cells with very gelati- 

 nous walls, similar to those of several other species of Monostroma, as M. arcticuin and 

 M. Grevillei. Their rooms are 6 — 10 ,w. thick in their longest diameter. The heads of 

 the clubs occnpy the middle of the frond, the shafts being placed towards the surface; 

 fig. 5 — 6. 



The rest of the frond is composed of cells with ellipsoidic or ovate rooms, the 

 long axis of which is at right angles to the surface of the frond. The whole wall of the 

 cell is covered by the chlorophyllous body; fig. 8. Downwards this part of the frond 

 is 30—40 ju. thick, the cell-rooms are 15 — 17 ,«. high and 8 — 10 /'. in diameter. At 

 the upper margin of the frond the thickness is somewhat less, 25 — ^30 f^., the rooms 

 of the cells are somewhat low^er and broader, almost round. The cells containing zoo- 

 spores have somewhat thinner walls than the vegetative ones, partition-walls of more 

 equal thickness, and somewhat larger rooms; fig. 9 — -10. 



Habitat. This species grows within the litoral zone on exposed coasts, somewhat 

 gregarious, but not in great numbers, attached to litoral algse, as Gorallina, Rhodo- 

 mela lycopodioides, Halosaccion, Fucacea3 or to serpulids and stones. I have found at 

 the beginning of August on the coast of Finmarken fully developed individuals with 

 zoospores as well as very young ones scarcely one millimetre in length. 



Geogr. Distrib. It is known as yet only from the north coast of Norway, the 

 northernmost point where it has been met with being Gjesvser, about Lat. N. 71°. 



Localities: Nordlanden according to specimens in Kleens herbarium; Finmarken: 

 Maasö local but rather abundant, Gjesvasr local and scarce. 



Monostroma angicava nob. 



M. thallo callo radicali adnato, initio vesicam pyriformem constituente, deinde expanso, membranaceo, 

 flaocido, lubrico, fusco-viride, demum pallescente, parce laciniato, margine piano, lacerato; parte monostromatica 

 45 — 60 /(. crassa, cellulis in sectione transversa tlialli lumiua cellularia vertioaliter rectaiigularia, angulis ro- 

 tundatis, 25 — 28 ,</. älta, 8 — 10 ((. lata pvcxbentibus, corpore chlorophylloso cellulas vegetativas iion explente. 

 Tab. 29. 



Description. The present species is attached by a callus radicalis. It has when 

 young the "form of a pear-shaped bladder, attaining a length of 5 cm. by 4 cm. in 



OQ 



K. Vet. Akad. Hftndl. Bd 20. N:o 6. - " 



