4,') 



Cellulee cylindricee in inferior! parte filorum ca. 11 ft latae 

 40 ft longse, in superior! 7 8// latse 40^ long*, chromatophorum 

 parietale, pyrenoide lateral!, instructum continentes. 



Sporangia sessilia, raro pedicellata in parte 

 basali ramorum uniseriata, monospora aut raro 

 bispora, ovalia, ca. 18 20/j. longa et 9 12/2 lata. 



The basal part of this species is immersed 

 in the mucilage and chalk incrustation of the 

 host plant (Liagora elongata). 



On germination the spore does not divide 

 and remains throughout undivided ; its diameter 

 is about 16/!/. After the germination it produces 

 endophytic filaments from its lower side ; these 

 creep downwards fixing themselves to the assi- 

 milating filaments of the host plant (Fig. 42 c). 



From the upper end an erect filament (or 

 sometimes two) is given off (Fig. 42 a) ; this is 

 at first undivided but after having grown so 

 that it is quite free of the Liagora tissue it 

 becomes branched. The ramification is some- 

 what slight. The branches are given off at an 

 acute angle and the branches themselves are 

 ramified in the same way giving the plant a 

 cluster-like appearance. 



Towards the summit the branches taper 

 into hair-like filaments the cells of which are 

 long and nearly colourless and soon die away 

 at the end (Fig. 42 a). 



The cells in the filaments are about 10 11 ft 

 thick and about 27 40 it long; near the base 

 the filaments are a little thinner, about 8 ft ; 

 in the hairlike ends the cells taper to about 

 7 80. 



The chromatophore (Fig. 43) is parietal, 

 often with elongations towards the wall of the 

 cell and it encloses a lateral pyrenoid. 



The sporangia (Figs. 42 a, b, Fig. 43) are 

 sessile, oval-ovate. They are about 9 12 ft 

 broad and 18 20 p. long. Monosporangia 

 mostly occur, but in a few specimens some 

 were divided by a transverse wall into two spores (Fig. 43). 



It is perhaps not impossible that Acrochaetium Barbadense 



Fig. 42. Acrochae- 

 tium occidentale 

 nov. spec, a, erect 

 filament with spor- 

 angia, b, part of a 

 filament with spor- 

 angia, the upper- 

 most divided into 

 two spores, the 

 lowermost emp- 

 tied, e, base of a 

 plant fixed to the 

 assimilating fila- 

 ments of Liagora. 

 (a, about 1'25 : 1; 

 b, 250:1; c, 200:1). 



