152 EHODYMENIACEiE. v 



now includino' four species, three of which are natives of the northern and one of 

 the southern hemisphere. It differs from the restricted genus Rhodymenia partly 

 by the structure of the nucleus, and partly by the zonate tetraspores. The generic 

 name here adopted was proposed in 1847 by Kiitzing, who probably overlooked 

 the name Wigghia which I suggested (Phyc. Brit. t. 32) some few months earlier. 

 Hoping to find some future opportunity of honouring the memory of Mr. Lilly 

 Wigg, I cheerfully acquiesce in the change. 



1. Rhodophtllis Veprecida,J. Ag. ; "frond dichotomo-decom pound, and pinnated 

 at the margin ; pinnte lanceolate or linear, ciliate ; cilia subulate, short or the 

 lono-er ones forked ; conceptacles densely clustered at the base of the cilia, often 

 confluent ; tetraspores numerous, lodged in the cilia." /. Ag. Sp. Alg. 2, p. 390. 

 {exd. Syn. Beechey.) 



Hab. Greenland, Agardh. 



" Two to three inches high ; the segments sometimes scarcely a line, sometimes 

 three or four lines broad, ciliate, the cilia either very short and subulate, or half an 

 inch long and once or twice forked. Conceptacles clustered around the base of the 

 shorter cilia. Colour rose-red or brownish. It scarcely adheres to paper." 



This plant I have not seen. Prof. J. Agardh seems to doubt whether it may not 

 more properly be referred to Calliblepharis. His quotation of " Rhod. ciliata ^. 

 microphylla, Bot. Beech. Voy. p. 164," is incorrect. 



IV. PLOCAMIUM. Lamour. (reform.) 



Frond sub-cartilagineo-membranaceous, linear, piano-compressed, pinnately decom- 

 pound (the pinnules alternately secund in pairs, or in threes and fours) : composed 

 of two strata of cellules ; the inner cellules longitudinal, oblong, the outer poly- 

 gonal, coloured, small. Conceptacles sessile or pedicellate, hemispherical, with a 

 cellular pericarp finally opening by a pore ; sporiferous filaments very numerous, 

 radiating in several tufts (some generally barren) from a basal placenta ; the fertile 

 forming masses of spores from their upper cells. Tetraspores lodged in proper 

 spore-leaves (stichidia), oblong, zonate. 



A beautiful genus, readily distinguished by the very peculiar ramification. The 

 frond in all is linear, distichously branched, two-edged or flat, sometimes membran- 

 aceous and furnished with a midrib, sometimes thickened and cartilaginous, pin- 



