linear, or slightly widened upwards; in common varieties (fig. 2) from two 
to four lines wide, sometimes much narrower or much wider; the axils 
rounded ; the apices obtuse, commonly truncate or subemarginate, some- 
times rounded, and occasionally slightly tapered. The margin is either 
entire and plane, or fringed with minute processes, which sometimes lengthen 
into proliferous foliations. Tudercles globose, generally abundant, and ses- 
sile along the margin of the segments; rarely scattered over the disc. 
Tetraspores forming cloud-like spots in the upper segments, oblong, divided 
by three transverse, zone-like lines. Colour in Var. a, a clear, transparent 
rose-red. Var. 8. is very much narrower, and more intricately and irregu- 
larly divided, of a darker, often very dark colour, opake, and thick, and 
forms entangled tufts. Var. y. is from half an inch to an inch in breadth, 
but little divided, cartilagineo-membranaceous, transparent, red when fresh, 
but becoming brownish, and not adhering to paper in drying; it produces 
marginal tubercles in abundance. Several other varieties are mentioned by 
Turner. 
Our plate represents three forms of this most variable plant, 
between the broadest and narrowest of which, innumerable states 
occur ; some of which, like our central figure, which may be re- 
garded as the normal state, are of a delicate rosy colour, trans- 
parent and membranaceous; while others are more or less in- 
crassated, and, especially when dry, of a brownish red. ‘The 
specimen represented at fig. 1. was gathered by Mr. Moore on 
the coast of Antrim, and Miss Hyndman has found, at Bun- 
doran, specimens of equal, or even greater luxuriance. 
Rhodymenia bifida differs from others of the genus, not merely 
in bemg more membranaceous, but in its fructification. The 
tetraspores, represented at fig. 9, are in it divided by transverse 
zones, like those of Plocamium, of Catenella, and of some other 
Algee ; while in Rhodymenia proper they are of the more common 
tri-partite kind. This character, in the present genus-making 
age, is perhaps of sufficient importance to justify the removal of 
R. bifida to a new genus; but I am not prepared to say how 
many, or whether any, others of the Rhodymenie have similar 
tetraspores. Should future observations confirm my suggestions, 
the new genus may be called Wigghia, in memory of Mr. Lilly 
Wigg “the instructor” in marine botany of Dawson Turner, and 
whose name, however uncouth, ought to be gratefully remem- 
bered by British Algologists. 
Fig. 1. RuopyMENTA BIFIDA ; unusually broad state. 2. The same; normal 
variety. 3. Var. 8:—all of the natural size. 4. Fragment of the frond, 
showing the surface cellules. 5. Segment with tubercles. 6. Vertical 
section of a tubercle. 7. Spores from the same. 8. Segment with tetra- 
spores. 9. Tetraspores :—all more or less magnified, 
