281 



Fig. 280. Polysiphonia ferulacea Suhr, J. Ag. 



Part of a filament with a nearly ripe cystocarp. 



(About 125:1). 



part of their thallus, 

 this also being the case 

 with P. ferulacea as 

 mentioned above. 



St. Thomas: The 

 reef between the Hurri- 

 cane Island and St. Tho- 

 mas. Store Nordsidebugt. 

 St. Groix: Northside. 



Geogr. Distrib.: 

 Mexico, West Indies, Au- 

 stralia. Sandwich Islands. 



Digenia Ag. 



1. Digenia simplex 



(Wulf.) Ag. 



AGARDH, G., Spec. Alg., 

 p. 389. Syst. p. 194. J. 

 AGARDH, Alg. Medit., p. 



147; Spec. Alg., vol. II, pars 3, p. 845. HARVEY, W. H., 

 Nereis Bor.-Am., part II, p. 30. FALKENBERG, P., 

 Rhodomelaceen, p. 159. pi. 9, figs. 25- 29. 



Conferva simplex Wulf., Cryptogama Aquatica, 

 p. 17. 



Cfr. DE-TONI, Sylloge Alg., vol.IV, p. Ill, p. 963, 

 where more synonyms are named. 



Regarding its anatomy and morphological 

 building upon the whole I refer to FALKENBEEG'S 

 exhaustive description 1. c. 



Digenia simplex occurs both in shallow 

 water and rather exposed places and in deep 

 water. The different localities determine to a 

 large extent the development of the plant; in 

 the first mentioned places the plant is robust, 

 of low growth, about 5 6 cm high and much 

 ramified, in deep water on the other hand I 

 have gathered specimens about 20 cm high and 

 nearly unbranched. 



Its stiff, tough stem is a very attractive 

 growing place for numerous small algaB which 

 commonly cover its thallus to such an extent 

 that only the quite young tips are free. 





Fig. 281. Digenia 

 simplex (Wulf.) Up- 

 per end of branch 

 with tetrasporan- 

 gia. (About 125:1). 



