F. Borgesen: Rhodophyceæ of the Danish W. Indies. 



193 



the upper ends of the filaments are about 250//. long and about 

 80 /i broad in the middle. 



The antheridial and cystocarpic conceptacles occur together 

 in the same plant (Fig. 181), while the tetrasporic conceptacles 

 occur in separate plants. 



As pointed out by Hauck (1. c.) the tetrasporic and female 

 conceptacles are developed in the basal joint in the uppermost 

 dichotomy. This joint is cuneate of shape ; it is large, of very 

 variable length, often more than 800 /^ 

 long; the breadth, at the upper end, 

 where the conceptacles are found, 

 seems on the other hand less variable, 

 about 250 /i. 



In the tetrasporic conceptacles 

 (Fig. 182) the hornlike prolongations 

 at both sides of the conceptacles 

 mostly consist of two nearly cylindri- 

 cal joints, while in the female concep- 

 tacles these horns consist only of a 

 single joint. But having seen so very 

 few plants I dare not say that this 

 is always the rule ; in the female 

 conceptacle the joints in the horn are 

 about 60 — 70// broad and about 300 /i 

 long, while in the tetrasporic the 

 lowest joint in the horns is about 70 fi 

 broad and 400/« long, the upper joint 

 a little thinner and shorter, about 

 230/« long. 



The joint with the antheridial 

 conceptacles are ovate— spindleshaped 

 and of smaller size than the tetra- 

 sporic and female conceptacles; they are about 250« long and 

 140// broad. They are formed in the uppermost joint of a branch; 

 the few antheridial filaments I have seen in the form from this 

 locality have all been short, consisting only of the antheridial 

 joint or, besides, of a single vegetative joint below. 



While I have had very few specimens growing upon Turbi- 

 naria at my disposal, I have collected a specimen of Zonaria 

 lobata at the shores of St. Croix upon which numerous specimens 

 of this small Jania were present (Fig. 183). Unfortunately the 

 exact locality of this plant is not known, but most probably it 



Fig. 182. Jania piunila Lanix. 

 Longitudinal section of tetra- 

 sporic conceptacle of specimen 

 found upon Turbinaria. 

 (About 75: 1). 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1 (1917). 



13 



