276 Dr. Greville on some new species of Sargassum. 



thin, membranaceous and translucent, the nerve slender, disap- 

 pearing beneath the apex ; pores not visible to the naked eye, 

 scattered over a space nearer to the nerve than to the margin, which 

 latter is destitute of them. Petioles short, with often a single 

 sharp tooth at the base of the leaf. Vesicles solitary, subsphe- 

 rical, on short compressed stalks, generally situated at the base 

 of the ramuli, but not unfrequently produced on the racemes 

 also, scarcely so large as hemp-seed. Receptacles axillary, linear- 

 oblong or fusiform, either undivided or forming lax racemes 2-3 

 lines long or more. They are generally entire at the lower part, 

 but sharply toothed towards the apex. Colour a dull, very pale 

 olivaceous green. Substance extremely thin, delicate and mem- 

 branaceous. 



This is a very interesting species, not contained in Dr. Wight's 

 collections, but kindly communicated to me at his special request 

 by its discoverer, James Campbell, Esq. of Madras. It is con- 

 spicuous by its very slender and delicate habit and pale olivaceous 

 yellow colour. The receptacles are sometimes solitary, sometimes 

 once-divided, but more generally form little clusters or raoemes, 

 the parts of which are much disposed to pass into foliaceous ex- 

 pansions. I have indeed seen receptacles on one raceme passing 

 in a proliferous manner into both vesicles and minute leaves. 



Vachellian^e. 



6. Sargassum debile (nob.) ; caule elongato, subcompresso, ramis 

 laxis, longissimis, simpliciusculis ; foliis membranaceis, lineari-ob- 

 longis, obtusis, dentatis, uninerviis ; vesiculis sphsericis axillaribus. 



Hab. in mari Chinensi prope Macao ; Vachell. 



Root unknown. Specimen in my possession 34 inches long, 

 and the character of the lower leaves indicates that they grew 

 near the base ; so that the whole plant may be from 3 to 4 feet long. 

 Habit extremely slender and weak. Stem somewhat compressed, 

 scarcely thicker than a sparrow's quill, giving off at irregular 

 intervals, for some inches above the base, a few filiform branches 

 2-3 feet long, of nearly the same thickness throughout, sometimes 

 more or less subdivided, but frequently simple, and along their 

 whole length bearing leaves and vesicles at intervals of from half 

 to three-quarters of an inch. Leaves thin, membranaceous, trans- 

 lucent, linear-oblong, obtuse, waved at the margin, sparingly 

 and irregularly toothed, attenuated below into the stipes, the 

 nerve conspicuous, very slender, disappearing below the apex; 

 pores minute, but visible to the naked eye. Vesicles axillary, 

 stalked, spherical, rather larger than the seeds of Lathyrus odo- 

 ratus, the stalks scarcely a line long, filiform. Substance mem- 

 branaceous and somewhat flaccid. Colour pale yellow-olivaceous 

 green. 



