CRYPTONEMIACE.E. 179 



gicas, it is by no means peculiar to Norway. It grows 

 on rocks, near low-water mark, during winter and spring, 

 and is annual. 



Genus LXXIX. AHNFELTIA. 



Frond horny, tapering, forked, composed of two strata of 

 cells ; those in the centre very slender, elongated, densely 

 packed ; those on the surface minute, arranged in vertical, 

 closely packed, short, necklace-like filaments. Spores minute, 

 arranged in masses (nucleoli) several of which are asso- 

 ciated together into a conceptacle-like cluster, which is im- 

 mersed in the frond ; tetraspores in external wart-like ex- 

 crescences surrounding the branches. 



The only British species of this genus was formerly 

 included in Gymnogongrus, from which it has been se- 

 parated on account of the much greater density of cel- 

 lular structure, and more rigid substance of the frond. 



Ahnfeltia plicata. The entangled Ahnfeltia. 



Fronds from six to ten inches or more long, horny, taper, 

 thread-like, irregularly branched, tangled ; axils rounded ; 

 terminal branches blunt at the tip. Fructification in wart- 

 like excrescences scattered over the branches : spores and 

 tetraspores being but seldom fully developed. 



This is a peculiar plant, and cannot easily be mistaken 

 for any other species. It is widely distributed both in 

 this country and elsewhere; it is perennial, and grows 

 on rocks and stones at various depths ; the fronds are 

 usually tangled together into a dense mass, they are of 

 a rigid, wire-like texture, of a dark purple colour, and 

 about as thick as fine twine. 



n 2 



