part cylindrical, except the apices, which are sometimes more or less com- 
pressed. Warts of fructification formed in various parts of the stem and 
branches, without order, at first appearing at one side of the branch, but 
soon extending round it, wholly formed of radiating moniliform filaments, 
whose upper joints are gradually transformed into elliptical, cruciate tetra- 
spores. Substance cartilaginous, or somewhat horny. Colour varying from 
a brown-red to a blackish-purple. 
Though hitherto placed, in British works, in the genus Gigar- 
tina, the structure of this plant is much more similar to that of 
Chondrus, in which genus it is placed by Professor J. Agardh. 
The structure, however, though, similar, is not identical; and as 
the tetrasporic fructification, which alone is known to us, offers 
some peculiarities, I adopt the name invented by Von Martius 
for this and the nearly allied G. plicata. The fructification is a 
most beautiful microscopic object, to which our figure does 
scanty justice. ‘The exquisite symmetry of the strings of tetra- 
spores, each marked with a white cross, and each inclosed in its 
glossy pellicle and brilliant as a ruby, can be but imperfectly 
shown on paper. 
Gymnogongrus Grifithsie, was first correctly distmguished by 
Mrs. Griffiths, whose name it worthily bears. It may at once be 
known from G. plicatus by the different habit, the more regular 
dichotomous branching, the fastigiate apices, and the substance, 
which is far less tough and horny. Agardh at one time confounded 
it with Gigartina acicularis, a plant of widely different structure. 
Its geographical range is extensive, though not quite so great 
as that of G. plicatus. It is dispersed on most of the Atlantic 
shores, from a high northern latitude to the tropics, but has not 
yet been found in the Southern Ocean, where G. plicatus occurs. 
It generally occurs within tide marks. 
Fig. GymNoconerus GrirFITHsl& :—9f the natural size. 2. Apex of a branch. 
3. Transverse section of the frond, cutting through a wart. 4. One of the 
strings of tetraspores. 5. Longitudinal section of the frond :—all more or 
less magnified. 
