ob lAWSON ON LEMANIA. 



most zealous and successful explorer, I at once recognized a 

 Leniania, remarkable for its extremely rigid, prominently monoli- 

 form, curved filaments, attenuated towards the base and apex, 

 and regularly marked tlirougliout by alternate bands, dark and 

 white, — agreeing, in fact, very well with Agardh's description 

 of L. variegata. I doubted not that the Belleville plant was 

 conspecific with that of Agardh, and probably the identical form 

 described in the "Species Algarum." Accordingly, I gave a 

 description of the plant in the Edm. New Phil. Jour., N. S., vol. 

 xviii. No. 1, July 1868. My description was scarcely published 

 when an opportunity presented itself of my personally visiting the 

 habitat for the Lemania, River Trent, along with its discoverer Mr. 

 Macoun, and a careful examination led to a modification of my "views. 

 The plant is indeed apparently the same as that described by 

 Agardh, but it is certainly not different specifically from Lemania 

 torulosa, with which Harvey had indicated the probable identity of 

 Agardh's plant (in Nereis.) 



Lemania, Bory. 



Generic character. — Eronds bristle-like, rising in clusters from a 

 common adherent base, cartilaginous or corneous, continuously 

 tubular, more or less nodose (brown, dull green, blackish or parti- 

 coloured), the tube membrane composed of two distinct closely 

 adherent strata of cells, those of the outer stratum minute, irregu- 

 larly polygonal, closely united pavement-wise in radiating groups, 

 those of the inner stratum rounded and not conformable, much 

 larger than the others. Spores (so called by authors) in seriated 

 stalked tufts, inside the swollen joints of the tube, and arising 

 either -from a central axis (according to Dr. W. J. Thomson), or 

 from the inner peripheral layer of cells, or from both. 



This genus, named Lemania by Bory, in honour of M. Lemain 

 of Paris, " a modest naturalist not less learned in botany than in the 

 other branches of science," embraces three species of aquatic alga; 

 of very remarkable aspect and structure, which grow attached to 

 stones, rocks, wood, &c., in the bottoms of shallow, rapid, fresh- 

 water streams. Unlike most fresh- water algiie, they have dense, 

 compact tissue, giving them firm consistence ; they are rich in 

 nitrogen, and when burned yield ammoniacal vapors. The plant 



