acute point. Barren specimens and those which produce tetraspores, have 
the forked branches usually naked ; in tubercle-bearing individuals, on the 
contrary, they are pinnated with short, horizontal, simple or forked ramuli, 
two to three lines long. Tubercles borne on the ramuli, either at their 
apices or more commonly below the point, which projects like a horn, soli- 
tary, or two or more together, usually very abundantly produced. Tetra- 
spores contained in dark coloured swellings of the branches immersed in the 
substance ; each sorus of large size, thick, containing innumerable chained 
cruciate tetraspores. Substance cartilaginous, shrinking very much in drying. 
Colour, a dull purplish or brownish-red. It does not adhere to paper in 
drying, unless after long steeping in fresh water. 
For splendid specimens, fresh from the sea, of this very rare 
Alga, I am indebted to Mr. Gilbert Sanders of Plymouth, who 
was so fortunate, towards the close of last year, as to re-discover 
an old habitat where the plant had been sought for many years, 
and not found since 1829. From one of Mr. Sanders’ newly 
gathered specimens our figure has been taken. 
The characters of this species are so strongly marked, espe- 
cially when in tubercular fruit, as is commonly the case, that it 
can scarcely be mistaken for anything else. In habit G. mammit- 
/osa comes nearest to it, but the channelled frond of that species 
affords a sufficient character. Barren specimens, or specimens 
with tetrasporic fruit, have rather the aspect of very narrow in- 
dividuals of Chondrus crispus, but they seldom occur except in 
company with unmistakable forms. 
All the specimens received from Mr. Sanders bore tubercles. 
I have since been favoured by Dr. Cocks, with specimens well 
furnished with tetraspores. The latter are contained in very 
dense sori, something resembling nemathecia, sunk in the sub- 
stance of the frond. 
Fig. 1. GIGARTINA PISTILLATA :—of the natural size. 2. Part of a branch 
with fertile ramuli. 3. Section of a tubercle. 4. Spores from the same. 
5. Section of a sorus. 6. Tetraspores from the same. 1. Transverse 
semi-section of a small portion of the frond :—all more or less highly mag- 
nified. 
