54 



Now and then from these cells erect filaments arise penetra- 

 ting through the epidermal layer of the host plant (Fig. 55). The 

 erect filaments reach a length of up to 500 /*. Below they are 

 about 7 8u thick and the length of the cells about 24^. Up- 

 wards they taper gradually and end with long nearly colourless 

 hair-like threads; the cells in these threads may reach a length 

 of up to 50 fj. or more and are 2 3^ thick. 



The erect filaments are multilaterally or very seldom oppo- 

 sitely ramified and the branches taper in the same way into hair- 

 like ends. 



The chromatophore (Fig. 55) is parietal with lobed margin 

 and with a lateral pyrenoid often projecting considerably into 

 the interior of the cell. 



The sporangia (Figs. 55, 56 , b) are placed at the base of 

 the branches or upon branchlets. They are nearly always pedi- 

 cellate, but now and then the uppermost sporangium is sessile. 

 The sporangia are oblong, about 14 // long and 8// broad. 



Found only once in a sheltered locality in shallow water. 



St. Thomas: The Harbour. 



20. Acrochsetium phacelorkizum nov. spec. 



Thallus caespitosus ad 1 mm altus et ultra, e filis endophy- 

 ticis et filis erectis ramosis sporangiferis compositus. 



Fila endophytica inter assimilatores hospitis immersa, saepe 

 aggregata, in superiori parte ramosa, e cellulis ca. 40 fj. longis et 

 2225, raro 21 ju. latis orta. 



Fila erecta, apicem versus sensim attenuata, a basi ramosa. 

 Kami in superiori parte filorum numerosi, sparsi aut saepe uni- 

 seriati. 



Chromatophorum parietale pyrenoide laterali instructum. 



Monosporangia sessilia, sparsa aut seriata, oblonga, 12 14 /* 

 lata, 22 24 (j. longa. 



This plant was found upon Codium elongatum and isthmocladum 

 among the utricles of which the basal part is immersed while the 

 upper free-growing filaments form tufts about 3 4mm high. 



Some small differences were present in my specimens; I shall 

 first describe those found in Codium elongatum. 



The basal part (Fig. 57) consists of proportionally very thick 

 filaments creeping downwards along the wall of the utricles and 

 between them; in the uppermost end the endophytic filaments 

 are ramified sending downwards from the lower end of the cells 



