256 Dr. Greville on some new species of Sargassum. 
divisions, the segments however being often nearly 2 lines long. 
The leaves bear a considerable resemblance to those of Sargassum 
bacciferum, but are much more numerous. 
18. Sargassum acutifolium (nob.); caule plano-compresso, distiche 
ramoso ; foliis linearibus utrinque attenuatis, acutissimis, integer- 
rimis, uninervibus, ad ramulos filiformibus ; vesiculis sparsis, sub- 
ellipticis, petiolatis, petiolis planis ; receptaculis compressis, lineari- 
oblongis, ad apicem dentatis. 
Sargassum acinaria, Ag. Sp. Alg. vol. i. p. 22 ?? 
Hab. in mari Peninsule Indiz Orientalis ; Wight. 
Root 1 have not seen. Plant probably 2 or 8 feet long. 
Stem (or probably primary branch) plano-compressed, a line or 
more broad, distichously branched; branches about an inch apart, 
8-12 inches long, flat like the stem, bearing ramuli 2-3 inches 
long, at intervals of 4 to 3 of an inch, which in their turn bear 
a smaller series upon which the fructification is placed. Leaves, 
the larger ones at the base of the branches, 2 inches im length, 
linear, acuminated at each extremity, entire, furnished with a 
nerve and a few scattered pores: the rest much smaller, almost 
filiform, those accompanying the fructification sometimes so slen- _ 
der as to be capillary. Vesicles scarcely half the size of hemp- 
seed, very sparingly developed, somewhat elliptical, on flat slender 
stalks, 2 lines or more long, mostly produced at the base of 
the racemes of receptacles. Sometimes a vesicle occurs at the 
extremity of a leaf. Receptacles minute, axillary, oblong or linear- 
oblong, compressed, generally toothed at the apex, forming more — 
or less divided racemes. Colour reddish black. Substance car- 
tilaginous. 
It is not without considerable hesitation that I separate this 
plant from Sargassum acinaria of Agardh. There are however 
differences, judging from his description, (and in the absence of 
authenticated specimens,) which seem to be sufficiently decisive. 
The stem in S. acinaria is said to be angular. In the specimens 
before me both it and the branches are clearly plano-compressed, 
‘and give off the ramifications in a distichous manner. ‘This 
character alone would remove my plant from the species above 
mentioned. The receptacles, described simply as cylindraceous 
in S. acinaria, are in the present plant, when fully deve- 
loped, more or less compressed, and toothed at the apex. The 
cauline leaves are not “lanceolate,” being too narrow to be 
termed even linear-lanceolate ; but this is a character so liable — 
to variation that much stress cannot be laid upon it. The 
racemes of fructification are truly axillary. The vesicles (in the 
specimens under examination) very few. Sargassum acutifolium 
is, from the abundance of the narrow leaves (which spread at a 
considerable angle), and also of the closely approximated tufts of 
