434 



in the basal part of the filaments and in the more vigorous ones, 

 higher up in the filaments and in the less vigorous the diameter 

 descreases to about 7 p. 



The chromatophores are not very developed; each consists of 

 a few irregularly bent and ramified narrow ribbons in each cells. 



7. Ectocarpus variabilis Vickers. 



VICKERS, A., Liste des algues de la Barbade (Ann. sc. nat. Bot.,ser.,9, 

 t. 5, 1905, p. 59); Phycol. Barbadensis, pi. XXXI. 



Upon some old leaves of Thalassia testudinum a small creep- 

 ing Ectocarpus was found forming small low tufts upon it. This 

 plant I think referable to the above mentioned species of the 

 late Mile. VICKERS. In one respect, to be sure namely the length 

 of the cells, it differed somewhat from her figure in which the 

 cells are drawn very short, mostly not twice their breadth, but 

 in the diagnosis of the species the length is said 

 to be three times the breadth which agrees better 

 with my plant. 



The plant, of which a piece is shown in Fig. 

 410, has creeping basal filaments from which the 

 erect ones arise. These have a diameter of about 

 9 12 fj. in their lower part decreasing gradually 

 upwards to about 7 j . In the lower part the cells 

 are about 22 30 40 /* long, higher up they be- 

 come slowly longer, in the upper ends of the 

 filaments reaching a length of more than 60 //. 

 The upper ends are not hairlike, the apical cells 

 have roundish summit, ending now and then in a 

 sporangium. 



A marked growing zone is not found. 

 In each cell several irregularly bent, narrow 

 ribbon-like, chromatophores are present. 



The plurilbcular sporangia are sessile or ped- 

 icellate, of rather variable size and shape, lance- 

 olate to oblong with broadly rounded summit; 

 about 60 p long and 27 ^ broad. 



Fig. 410. Ecto- 

 carpus variabliis 



Vickers. 

 (About 250:1.) 



The plant was found in a lagoon-like locality in the 

 harbour of St. Thomas. 



Geogr. Distrib.: Barbadoes. 



