405 



in the greater thickness of their main branches as also in the faet 

 that, on a closer examination of the material, sporangia have oc- 

 casionally been found which were longer in form. In fig. 67 I have 



Fig. 67. Ectocarpus siliculosus (Dilhv.) Lyngb. f. arcta (Kutz.)- Different parts of the plant; compare text. 

 a, c, d 100 : 1 ; b 60 : 1 ; e, / 160 : 1. 



shown some portions of a plant belonging to this form which was 

 found in Vaagfjord growing epiphytic on Zostera marina. As mav 

 be seen the sporangia are in the main short, nearly ovate or oval 

 and most commonly sessile, but stalked examples occur intermingled. 

 The stalk is sometimes composed of a single cell, sometimes of 

 several. Sporangia more long in form occur here and there (fig. 67, 



12 ( i - 



