198 BRITISH SEA-WEEDS. 



Genus XCIII. SPYRIDIA. 



Frond thread-like, compressed, much branched, composed 

 of a single, jointed, thick-walled tube, coated externally with 

 small, many-sided cells, and beset with slender, minute, 

 thread-like, jointed ramelli. Spores oblong, in clusters, several 

 of which are enclosed in a membranous pericarp, in concep- 

 ;acles borne at the ends of short branches ; tetraspores 

 ripartite, arranged singly along the branchlets. — Spyridia, 

 from the Greek spuris, a basket. 



The six or seven species which are at present included 

 in this genus are all natives of warm or temperate lati- 

 tudes, and only one of them belongs to our marine 

 flora. 



Spyridia filamentosa. The filamentose Spyridia. 



Fronds from a few inches to a foot long, and from once to 

 twice as thick as a bristle, thread-like, much branched ; 

 branches alternate, repeatedly divided, thickly set with short, 

 jointed, acute branchlets. 



This species is widely distributed throughout the 

 tropics of both hemispheres, and as far north as the 

 south of England. Extending over so wide a range of 

 latitude, it is not extraordinary to find it varying much 

 in size and luxuriance; at the same time its general 

 characters are distinct and sufficiently constant. It grows 

 near low-water mark, is perennial, and in perfection in 

 summer. It has been found in several localities on our 

 south coast, and as far north as Anglesea. I have 

 gathered it in moderate abundance in Jersey. 



