F. Børgesen: Rhodophyceæ of the Danish W. Indies. 265 



ners of the spines as adventitious branches (Falkenberg, 1. c. 

 p. 227). Further the branchlets have mostly spines from their 

 base upwards. 



The ramuH with tetrasporangia are very spiny; the tetra- 

 sporangia are often found too in the summit of the branchlet 

 which bears the ramuh. 



The cystocarps are placed upon a thick spine-like ramulus; 

 Falkenberg who has followed the development in the case of 

 A. Delilei says it is a leaf (1. c, p. 230). 



The cystocarps are ovate-urnshaped bodies, with a large 

 opening at their summit. 



Only gathered once in shallow water in a somewhat protec- 

 ted locality. 



St. Thomas: The Hurricane Island in the harbour of Charlotte Amaüa. 



Geogr. Distrib.: West Indies, Florida, Brazil, Cape, Japan etc. 



Subfam. 3. Polysiphonieæ. 

 Polysiphonia Grev. 



As most of the descriptions of the Polysiphonias found in 

 the West Indies and surrounding waters are rather deficient and, 

 without access to original specimens, any precise determination 

 is therefore difficult, I fear that some of my determinations are 

 not quite exact. 



The following six species have been found in the area exami- 

 ned; they can be arranged in the following way: 



A. With axillary branches. 



a. With four pericentral cells. 



a. Diameter of the filaments about 90//. 



1. Polysiphonia havanensis. 

 ß. Diameter of the filaments about 35 ß. 



2. Polysiphonia spec. 



b. With 5—7 pericentral cells. 



3. Polysiphonia variegata. 



B. Branches formed without connection with the trichoblasts. 

 a. With four pericentral cells. 



a. Diameter of the erect filaments about 100//. 

 I. With nearly spherical cystocarps. 



4. Polysiphonia sphærospor a. 

 II. Cystocarp urceolate. 



6. Polysiphonia macrocarpa. 

 ß. Diameter of the filaments about 200—800//. 



6. Polysiphonia ferulacea. 



