168 BRITISH SEA-'\\lEEDS. {lSIelanosperme(C. 



Genus XXXII. RALFSIA, Berkeley, 



Gen. Char. Frond coriaceo-crnstaceous, fixed by its inferior 

 surface, orbicular, concentrically zoned ; composed of densely 

 packed, vertical, simple filaments. Fructification, depressed 

 warts, scattered over tlie upper surface, containing obovate 

 spores fixed to tlie bases of vertical filaments. — Ralfsia, in 

 honour of John Ealfs, Esq., of Penzance, a most acute botanist, 

 whose discoveries among the minute Algae, especially the Dia- 

 tomacea, have thrown great light on that little-known branch of 

 botany. — Harvey. 



I. Ralfsia ATiiiiiucosA, Arcsclwug . 



Hab. Common on the rockv shores of the British Islands. 

 Perennial. AVinter. Though very common on the Ayr- 

 shire coast, and still more so in Arran, it is not generally 

 known, as it attracts not notice by its beauty. 



Genus XXXIII. LEATIIESIA, Gray. 



Gen. Char. Frond globose or lobed, fleshy, composed of 

 jointed, colourless, dichotomous filaments, issuing from a central 

 point; their spines, which constitute a fleshy coating to the 

 frond, coloured and tufted. Fructification, oval spores attached 



