F. Børgesen: Rhodophyceæ of the Danish W. Indies. 225 



I have not been able to see with certainty, in the rather 

 scanty material, whether the carpogonial branch consists of 3 or 

 4 cells. Schmitz (1. c.) in his diagnosis of the genus Seirospora 

 describes the carpogonial branch as most often 4-celled, but in 

 Seirospora interriipta he found (1. c. p. 280, note 3) the carpogonial 

 branch consisting of 3 cells only. 



After fertilization both the auxiliary cells begin to divide 

 and produce the ramified, sporogenous fdaments of which the 

 cystocarps consist. 



The antheridial stands are distributed in the same way as 

 the tetraspores, placed on the uppermost and inward side of the 

 mother-cell (Fig. 210 D). They consist of quite short branchlets 

 which bear the spermatangia. Most often they grow quite closely 

 together in dense tufts, sometimes too, as Fig. 210 E shows, more 

 scattered. 



When I described this plant I had not come across the para- 

 spores. Having now examined some more collections of algæ I 

 have twice found plants with paraspores which I refer, without 

 hesitation, to this species. In one of the collections (from St. 

 Thomas, Fig. 212) the specimen with paraspores was found 

 together with other fructiferous parts of this plant; in the other 

 (from St. Croix) the paraspore-bearing specimen was not found 

 in company with any other specimen of this species. 



The branchlets forming the paraspores occur in the same 

 places as the tetrasporangia, viz. at the upper and inner side of 

 the cells in the filaments. They consist of short cells filled with 

 reserve nutriments. The cells have thick walls, and become, when 

 ripe, nearly spherical. The diameter of the paraspores is about 

 18—20 (ji. 



This species has been found epiphytic upon Gracilaria Blod- 

 gettii in a depth of about 15 fathoms and besides I have found 

 a few specimens intermingled among Cladophora and Callithamnion 

 in about the same depth. Once it was found washed ashore 

 growing upon an old piece of Sargassum vulgare. 



It has been found in several places in the sound between St. Thomas 

 and St. Jan: e. g. off Christiansfort. St. Thomas in the sea to the west 

 of Water Island. St. Croix: near the estate Lt. Princess (washed ashore). 



Geogr. Distrib.: Hitherto not found in other regions. 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1 (1917). 15 



