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



183 



Fig. 171. Amphiroa rigida Lamx. var. 



Antillana nov. var. Part of a regularly 



dichotomous thallus. (About 2 : 1). 



and taper evenly to the sum- 

 mit where often the diameter 

 scarcely reaches half the 

 length of the above mentioned 

 size. In the basal part the 

 colour of the dried specimens 

 is a ligth red-violet, towards 

 the top almost white with a 

 blue-violet tinge. 



The branches are spread- 

 ing, the angle of the dicho- 

 tomy being mostly obtuse, 

 though sometimes acute. 

 The joints are long, often 

 reaching a length of more 

 than one cm., cylindrical, and 

 in their upper end, bifurcate, the nodes often (not always) occurring 

 at rather a long distance above the dichotomy, one or sometimes 



even 2 mm. above it. In the 

 upper end of the frond the 

 dichotomy often does not 

 occur, but the filaments are 

 divided by nodes in a similar 

 way as that found in the 

 ramified parts of the thallus. 

 Of the illustrations I have 

 seen of this species my plant 

 seems to come nearest to the 

 above mentioned figure of 

 Zanardini (Fig. B 1), but the 

 ends of the branches of my 

 plant are less tapering and 

 not so curved as the ones in 

 Zanardini's figure. 



From SoLMS - Laubach's 

 description (1. c. p. 7) my 

 plant seems to differ some- 

 what. He says: "Sie zeich- 

 nen sich durch unregelmässige Verzweigung und durch spitzwink- 

 lige, wenig divergente Richtung der Aeste aus, daher denn stets 

 kompakte dichte Rasen gebildet werden". As described above 



Fig. 172. Amphiroa rigida Lamx. var. 

 Antillana nov. var. Part of a more 

 irregularly ramified thallus. (About 2: 1). 



