424 



form which I think referable to this species (Fig. 405). It was 

 growing together with the above mentioned Chaetomorpha forms. 

 It is fixed to the rocks etc. by means of a larger or shorter 

 basal cell formed by throughgrowing of the lowermost cells. 

 The cells in the vegetative part of the filaments are about 70 80 

 |u thick and two to four times as long. The zoosporangia are often 

 a little swelled in their middle, about 85 \\. thick and two to three 

 times as long. 



St. Jan: Christiansfort. 



Rhizoclonium Ktitz. 



Upon steep rocks in an exposed place near high water mark 

 or a little above some Rhizoclonium forms were found showing 

 several peculiarities. They occured as parts of an interesting 

 association of alga?, answering to the North-Atlantic Bangia- 

 Urospora Association of the Faroes 1 ) or the Bangia-Urospora- 



Ulothrix Association of Clare 

 Island 2 ). The members of the 

 tropical association were: a small 

 Enteromorpha plumosa, Pylaiella 

 fulvescens and several species of 

 Chaetomorpha and Rhizoclonium. 

 It is a well known fact that 

 the genus Rhizoclonium is especi- 

 ally characterized by the pre- 

 sence of lateral rhizoids occur- 

 ring more or less abundantly, 

 though sometimes nearly or 

 quite wanting, and by the ab- 

 sence of the original basal 

 end-rhizoid, this having been 

 found a few times only. 

 In the present forms (compare figs. 406 and 407) all the many 

 specimens examined had no lateral rhizoids at all and in most 



Fig. 406. Rhizoclonium Kochianum 



Kiitz. Different forms with bases of 



two plants. (About 260:1.) 



x ) BORGESEN, F., The Algae-vegetation of the Faeroese coasts (Botany 

 of the Faeroes, Part III, 1905, p. 719). 



2 ) COTTON, A. D., Marine Algae, Clare Island Survey 15, p. 30. (Proceed- 

 ings Royal Irish Acad., vol. 31, 1912). 



