45 



Jessen at the northern side of Sermersok. They form tufts 

 1 — 2 cm. high, incurved branches are rather frequent, and the 

 sporangia occur singly. On the whole the specimens mostly 

 agree very well with Ä. incurva^ but they differ from it by the 

 occurrence of rhizoids in the uppermost part of the frond and 

 by having the branches of last order sometimes given off at 

 right angles. The rhizoids occur somewhat irregularly in the 



Fig. 5 Acrosiphonia incurva Kjellm. 



Two fragments of the specimens from Sermersok. Compare the text. 



a contains two singly occurring sporangia; the branch to the left shows at 



the base a normal rhizoid, at the apex an abnormally developed one. 



47: 1. 

 b shows a single sporangium and abnormally developed rhizoids becoming 



branches. 13:1. 



uppermost part of the frond, and sometimes shoots from the 

 upper ends of the cells, that is shoots which should have been 

 branches, are developed as rhizoids, and vice versa, shoots from 

 the lower ends of the cells, that is shoots which should have 

 been rhizoids, are developed as branches. Fragments of main 

 branches with young branches and young rhizoids occur loosely 



