2 NEW BRITISH ALG.E. 



the shore at the same time as Seriospora Griffithsiana. I once met 

 with a specimen there which had elliptical lateral tetraspores, but it 

 has been unfortunately lost. 



EXPLANATION OF PLATE XI. 



1. — The entire plant. 



2.— Plumule magnified X 20. 



3.-Pinnule magnified X 100 ( «• | elliptical cells on rachis of plumule. 



° I o. 6 ditto on ultimate branchlet. 



4. — Tuft of moniliform cells. 



5. — Portion of base of stem showing the coating of branched and jointed fila- 

 ments. 



Nitophyllum thysanorhizans. N. S. — General characters : Frond, 

 1-2 inches long, of a thin membranaceous substance, very flaccid, 

 and of a pale rose colour, glossy when dry, and adhering closely to 

 paper. Frond much branched, branches between pinnate and 

 furcate, from one to two lines broad, slightly dilated upwards ; the 

 terminal segments generally two-lobed, one lobe being shorter and 

 smaller than the other. The fronds are everywhere fringed, at 

 intervals of about one line, w T ith minute cellular processes, which 

 develop roots at their extremities, and by these the plant adheres 

 to other Algre. 



Microscopical structure : Cells polygonal, becoming smaller 

 and quadrate at the margin of the frond ; the cellular processes 

 are composed of large elongate polygonal cells, which become 

 smaller and very dense toward the point from which the roots arise. 

 A network of minute veins traverses the whole of the frond, and is 

 especially noticeable in the ultimate segments, the veins being 

 formed of a single row of narrow, somewhat cylindrical cells. 

 Tetraspores distinctly tripartite, collected into definite rounded sori 

 in the apices of the ultimate segments. Capsular fructification not 

 yet met with. 



Habitat : Thrown up on a mud- bank at Torpoint, and at Mount 

 Edgecumbe, near Plymouth. Perennial ? 



This interesting little plant has probably been overlooked for 

 many years as a variety of Rhodymenia bifida, under which name I 

 have several times received it, and have also seen it among the 

 Alga3 collected, by the late Dr. Cocks, and now in the possession of 

 the Linnean Society. This mistake has most likely arisen from 

 the similarity of its branching to that of R. bifida, and perhaps 

 also from the rare occurrence of its tetraspores. From R. bifida, 

 however, and from R. cristata, which it also resembles, it is abun- 

 dantly distinguished by its definite sori, and tripartite tetraspores. 

 From Nitophyllum pnnctatum, to the narrow forms of which there 

 is a close resemblance in colour and general appearance, it is 

 separated by the tetraspores forming sori in the apices of the frond 

 only, and by its fimbriate margin. 



N. thysano?'hiza?is has not, so far as I have been able to ascertain, 

 been found in any other locality than the one above mentioned. It 

 is thrown np there in seme abundance in July, but the tetraspores 



