Dr. Greville on some new species of Sargassum. 217 
_ The only specimen—and it is a mere fragment—which I have 
‘seen of this Alga was disentangled from some other species. 
There appears to be a disposition in the leaves towards the ends 
of the branches to become incurved, but this may not be a per- 
manent character. 
A 
14. Sargassum Wightii (nob.) ; caule compresso, distiche ramoso ; 
foliis anguste lanceolatis, integerrimis; vesiculis ellipticis, apicu- 
latis, longe petiolatis, petiolis planis, dilatatis ; receptaculis linea- 
ribus, compressis, ramosissimis, in racemo amplo subtruncato 
 aggregatis. 
Wight in herb. no. 12 & 13. 
Hab. in mari Peninsule Indie Orientalis ; Wight. 
Root an expanded disc, throwing up several mostly undivided 
stems from 1 to 2 feet in length, or probably more, giving off 
branches in a distichous manner, at intervals of half an inch or 
more; the lower ones are several inches long, becoming gra- 
dually shorter, and more remote as they approach the summit : 
the fruit-bearing ramuli are very short, and, like the rest, di- 
stichously arranged. Leaves from 1 to near 2 inches in length, 
narrow-lanceolate, sometimes almost linear-lanceolate, nearly 
equally attenuated at each extremity, acute, quite entire or 
obscurely repando-dentate, furnished with a somewhat faint nerve 
and a few scattered pores. Vesicles about the size of the seed 
of Lathyrus odoratus, elliptical, apiculate, on long dilated folia- 
ceous stalks, in young plants arising from the axils of the cau- 
line leaves ; afterwards accompanying the fructification but spa- 
ringly, and generally taking the place of a leaf. Receptacles 
axillary, filiform, compressed, very much divided, the exterior 
branches the longest, so that the racemes have a cymose or tassel- 
like appearance. The racemes vary much in size, being dense, and 
- not more than 2 or 3 lines long in some plants; in others half 
an inch and much more lax. Colour dark, olivaceous, the recep- 
tacles black when dry. Substance slightly cartilaginous. 
_ In some specimens, the branches, besides producing axillary 
racemes, have the appearance of terminating in a larger raceme, 
an effect which seems to be produced by the ultimate leaves being 
converted into receptacles, the whole preserving the truncate and 
tassel-like outline of the axillary racemes. 
For this fine and very striking Alga I have reserved the name 
of the excellent and indefatigable naturalist from whom I received 
it. It is quite unlike any other species with which I am ac- 
quainted. 
15. Sargassum cervicorne (nob.); caule compresso, distiche ramoso ; 
foliis late lineari-lanceolatis subintegerrimis, superioribus atque in 
ramis fertilibus brevioribus, lanceolatis, plus minusve dentatis ; 
