— 10 



in rather sheltered locahties where it swings to and fro following 

 the feeble motion of the sea. It was collected in the middle of 

 February having at that time ripe or nearly ripe cystocarps. 



Only found once on the southern coast of St. Croix: at 

 Long Point. 



decomposito-pinnato , non corticata. 



Callitlianmioii cordatum nov. spec. 



Caespites 2— 4 cm. vel paulo ultra alti; fronde erectiuscula alterne 



Articulis diametros binas vel 

 trinas longis, 200^ eras- 

 sis; ramulis superioribus 

 tenuioribus ca. S/x crassis, 

 incurvis. Tetrasporangiis 

 in interiore latere pin- 

 nularum sitis , oblique 

 obovatis, triangulatini di- 

 visis. Cystocarpia gemi- 

 na, cordata, plana ssepe 

 tantum ex uno strato car- 

 posporarum constructa. 

 E \ )| / ) ^ XT // ^ I 



Frond 2— 4cm. high; 



the main stem is below 



nearly straight with few 



side branches, becoming 



more flexuous and richly 



ramified higher up; near 



the top the axis is effaced. 



The base (Fig. 5 A) 



consists of very short, 



thick- walled cells, the wall 



about 18// thick and the 



whole cell as much as 



200 fji or more thick. 



From the lowest cells 



near the base rhizoid-like 



branches grow downward 



and contribute to fix the 



plant. Higher up the cells grow longer becoming at the same time 



thinner, at first twice as long as broad (long. cell. = 300/^; lat, 



cell, = 160 /i), until nearer the top they are 5—8 times as long 



as broad (long. cell. = 400//, lat. 50/^). The uttermost branches 



are often arch-shaped, bent inwardly (Fig. 5 C, Fig. 6); they are 



Fig. 5. Callithamnion cordatum nov. spec. 



A, base of the plant (25:1). B, end of branch ^vith hair 

 (100:1). C, branch with tetraspores (50: 1). O, tetraspore 

 (150:1). E, branch with antheridia (00:1). F, cell witli 

 antheridia (150:1). (?, cystocarps (60: 1). //, young procarp 

 (150:1). /, older procarp with fully developed trichogyne 

 (150:1). K. transverse section of a cystocarp (60:1). 



