On the Marine Algæ from North-East Greenland. 



105 



as the breadth or a little greater, in other cases smaller; in the 

 upper part of some crusts the cells were very low, several times 

 broader than high. Transversal fusions between the cells, especially 

 those of the basal layer, but also those of the vertical filaments 

 (fig. 3 .4) occur here and there. 



Some crusts bear sori of sporangia, with unripe or fully devel- 

 oped sporangia; in other cases the sori had fully developed para- 

 physes but no sporangia, these having probably decayed. Ripe 

 sporangia, found in August, were 30 — '62 ц long, 19 — 20 p. broad. 



Some other crusts, collected in August and September, bear 

 antheridia, which organs were hitherto unknown in this genus. 

 They covered a great part of the surface of the frond as a continuous 

 layer of much greater 

 extent than the spor- 

 angial sori. The an- 

 theridia (spermatan- 

 gia) are obovate, 10 

 — 11^« long, 4// broad. 

 In a лег11са1 section 

 the vertical cell-rows 

 are seen bearing at 

 their upper end one 

 or usually two cells, 

 which are smaller and 

 richer in plasmatic 

 contents than the ve- 

 getative cells and bear 

 the antheridia. These 

 cells (Svedelius's sper- 



matangial mother-cells) bear at the top two antheridia, a terminal 

 and a lateral one, or perhaps more. By the development of the 

 antheridia the thick cuticula is lifted and finally thrown off by the 

 developing antheridia. The spermatia are, like the antheridia, obo- 

 vate and contain a very distinct nucleus, lying in the upper part or 

 the middle of the cell. 



Carpogonia were not observed. 



Log. Along Ivoldewey Island; entrance to the liarbour {d and spor.); 

 off Baadskæret and along W. Havnenæs, ca. 38 meters (с? and spor.) 



В 



д 



с 



Fig. 3. Rhododermis elegans, sections of male plant. 



A, Vertical section of crust with antheridia. B, an- 



theridia-bearing cell with two antheridia. C, Vertical 



cell-row with two antheridia-bearing cells. 830 : 1. 



Fam. Ceramiaceœ. 

 Antithamnion Næg. 

 9. A. Plumula (Ellis) Thur. ß, boréale Gobi 



к. Rosenvinge (1898 I) p. 21, Jonsson (1904) p. 8. 



