CHORDAKIACEiE. 73 



gradually decreasing towards the tip, where they are very 

 short. Spores linear-oblong, without stalks, at the base of the 

 threads. 



This species grows on Cystoseira ericoides, and has not 

 hitherto been very frequently found. It is called E. 

 attenuata in the ' Phycologia Britannica.' 



Elachista velntina. Velvety Elackista. 



Patches velvet-like, spreading, of indefinite shape ; outer 

 threads short, of the same thickness throughout, the inter- 

 vals between the joints about once and a half as long as the 

 threads are broad. Spores egg-shaped, dark olive-coloured, 

 with wide transparent margins, borne on short slender 

 stalks. 



This species is found on the thongs of Himantha- 

 lia lorea, and sometimes in company with E. scutu- 

 lata, which it very much resembles. It also grows on 

 Fuci. 



Elachista Grevillei. Greville's Elachista. 



Tufts brush-like ; threads cylindrical, slender, elongated, 

 the intervals between the lower joints short, those between 

 the upper rather longer. 



This species is not mentioned in the ' Phycologia,' but 

 was described by Dr. Harvey in the ' Natural History 

 Review' for 1857. It grows on Cladophora. 



Genus XXXI. MYBIONEMA. 



Pronds minute, parasitical, composed of two series of 

 jointed threads, the inner branched and spreading over the 

 surface to which the plant adheres ; the outer simple and 



