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LIST OF THE BEITISH 



LXVII. FuRCELLARlA. 



Root branching. Frond cylindrical, dichotomous, 

 cartilaginous. Favelte immersed in the pod-like swol- 

 len extremities of the branches. Tetraspores similarly 

 immersed. 



1. Furcellaria fastigiata. 



LXVII I. DUMONTIA. 



Frond cylindrical, tubular. Fructification: — 1. Clus- 

 ters of obovate spores, attached to the inner surface of 

 the membrane of the frond ; 2. Roundish tetraspores 

 among the surface -cells. 



1. Dumontia filiformis. 



LXTX. Halymenia. 



Frond compressed or flat, gelatinous, membranaceous. 

 Fructification spherical masses of spores immersed in 

 the frond. 



1. Halymenia ligulata. 



„ var. latifolia. 



