216 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



Je n'ai pas vu de cystocarpes". Perhaps she has had the pre- 

 sent plant before her. 



The plant was dredged in deep water in a depth of about 

 30 meters. 



St. Jan: Off Annaberg. 



Subfam. 4. Callithamnieæ. 

 Callithamnion Lyngb. 



1. Callithamnion cordatum Børgs. 



Børgesen, F., Some new or little known West Indian Florideæ (Bot. 

 Tidsskrift, vol. 30, 1909, p. 10). 



This plant is an epiphyte forming small, rosy, shrub-like tufts 

 upon the host plant. 



It is not corticated; however, from the basal cells of the 

 vigorous branches in the lower-most part of the thallus a 

 single long rhizoid is often developed. It grows 

 do\NTiwards along the wall of the large cells in the 

 main stem (Fig. 201). These rhizoids are composed 

 of nearly cylindrical cells about 150 fi long and 

 25 ft broad. 



The frond reaches a height from 2 — 4 cm. ; the 

 main stem is at the bottom part nearly straight 

 with few branches, becoming more flexuous and 

 richly ramified higher up ; near the top the main 

 axis disappears (Fig. 202). 



The base (Fig. 203 A) consists of short cells, 

 their walls often reaching a thickness of 18 /j or more, 

 the diameter of the whole cell measuring about 200 /i. 

 From the cells near the base rhizoids grow down- 

 wards and assist in fixing the plant. 



Higher up in the main stems the cells grow 



longer becoming at the same time thinner, at first 



twice as long as broad (long. cell. = 300^; lat. cell. 



= 160^), and then nearer the top 5 — 8 times as 



long as broad (long. cell. = 400//; lat. cell. ^= bOju). 



The uppermost branches are much thinner, only S/j. 



thick; they are often arch-shaped and bent inwardly (Fig. 204). 



The ramification is alternate, in the upper part subdichotomous. 



In my previous description I have said that hairs, as a rule, 



are absent; this is the case, too, in the older part of the thallus 



Fig. 201. 

 Callitham- 

 nion corda- 

 tum Borgs. 



Rhizoid 

 growing out 

 from base 

 of a brancli. 



(About 



170 : 1). 



