256 Dr. Greville on some new species of Sargassiim. 



divisions, the segments however being often nearly 2 Unes long. 

 The leaves bear a considerable resemblance to those of Sargassum 

 bacciferum, but are much more numerous. 



18. Sargassum acutifolium (nob.); caule piano- 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 ? .-* 

 Hah. in mari Peninsulse Indise Orientalis ; Wight. 



Root 1 have not seen. Plant probably 2 or 3 feet long. 

 Stem (or probably primary branch) piano -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 |^ to ^ 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 in 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 piano-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, mote or less compressed, and toothed at the apex. The 

 cauline leaves are not ^Hanceolate,^^ 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 



