144 RHODYMEiSlACE.E. v. 



ramelli, which often overtop it, and completely hide it. Antheridia frequently 

 occu})y the position of tetraspores. They consist of minute spherical tufts of 

 dichotomous, radiatins; filaments attached to the sides of the ramelli. I have not 

 found tetraspores on the American specimens. When quite fresh the frond is of a 

 beatiful rosy red, and sometimes this is partially preserved in drying ; but more 

 commonly, especially if the specimen be suffered slightly to decay, it turns dark 

 brown or blackish in the drj'ing process, and stains the paper of the same colour. 

 The substance is very flaccid and tender, soon decaying in fresh water. 



I was at first disposed to regard our American plant as distinct from the Euro- 

 pean W. penicillata, and had proposed to call it W.JiUcina, but a careful comparison 

 of numerous specimens has shown that the distinctions on which I had relied are 

 insufficient. 



Plate XXXIV. B. Fig. 1 and 2, different varieties of Wrangelia petiwillata, the 

 natural size. Fii/. 3, one of the smaller branches, with its whoi'led ramuli ; Jig. 4, a 

 small portion of the stem or of a large branch ; fig. 5, cross section of the same; Jig. 

 6, a fertile branch, with terminal involucre and nucleus ; Jig. 7. nucleus (not quite 

 correctly drawn) ; Jig. 8, spoi'es from the same ; Jig. 9, vertical view of a whorl of 

 ramuli, to shew the excentric position of the branch: the latter figures more or 

 less magnijied. 



2. "Wrangelia plebeia, J. Ag. ; " fronds corticate, sub-pinnately branched, and 

 verticillately ramellose at the nodes, penicillate at the apex ; ramelli repeatedly 

 dichotomous, the terminal cells acute, articulations of the ramelli contracted at the 

 dissepiments, 4 — 5 times as long as broad." /. Ag. Sp. Alg. vol. 2, p. 708. 



Hab. At Vera Cruz, Mexico, Liebman. 



Probably, as Professor Agardh suggests, only a variety of the preceding species. 



Order X. RHODYMENIACE^. 



Ehodymeniece, J. Ag. Sp. Gen. and Ord. Algarum, p. 373. Part of Wwdymenia- 

 cecB, Harv. Man. Ed. 2, p. 120. Part of Sphoirococcoideoe and Delesseriacece, Auct. Sfc. 



Diagnosis Purplish or blood-red sea- weeds, with an inarticulate, (flat, com- 

 pressed or filiform) membranaceous frond, composed chiefly of polygonal cells ; 

 the surface cells forming a continuous coating. Nucleus lodged in an external 

 conceptacle, simple or formed of several nucleoli. Spores at first associated ia moni- 



