434 Dr. Greville on some new species of Sargassum. 



tervals of half an incli to an inch. These branches produce others, 

 which are more or less subdivided in their turn, so as to give the 

 ramification generally a bushy fasciculate character. Leaves an 

 inch long, somewhat more than a line broad, linear-lanceolate, 

 acute, gradually attenuated from the middle to the petiole, very 

 irregularly toothed, and that almost exclusively in the upper part, 

 rarely subentire, furnished with pores and a slender nerve which 

 disappears below the apex. Vesicles larger than the seed of 

 Lathyrus odoratuSy accompanying the receptacles, elliptical, often 

 mucronate, supported on flat stalks nearly half an inch long, 

 sometimes becoming even longer and decidedly foliaceous. Re- 

 ceptacles axillary, 1-2 lines long, club-, or linear-wedge-shaped, 

 somewhat compressed, often incurved, toothed, especially at the 

 outer margin and apex, and forming a rather lax sparingly di- 

 vided raceme. Colour blackish brown in the dry state. Sub- 

 stance rigid. 



The solitary specimen from which I have drawn up the above 

 description was mixed with Sargassum pyriforme, Ag., to which 

 it bears no inconsiderable resemblance in general habit, and 

 especially in the form of the vesicles. Both the leaves and fruc- 

 tification, however, at once separate it from that plant. With 

 Sargassum Swartzii, Ag., it has a nearer affinity, but is readily 

 distinguished by the much shorter leaves and elongated, toothed 

 receptacles. 



EXPLANATION OF PLATE XIIL 



Sargassum lanceolatum. 



Fig. 1. Termination of a branch. 



— 2. Leaf, vesicles and raceme, sliglitly magnified. 



— 3. Vesicles. 



— 4 & 5. Racemes, magnified ; one of the receptacles terminating in a 



foliaceous expansion and vesicle. 



Sargassum acanthicarpum. 



Fig. 1. Termination of a branch. 



— 2. A portion with receptacles, one of the leaves being converted into a 



vesicle. 



— 3. Leaves from the base of the stem close to the root. 



— 4. Vesicles. 



— 5. Leaf and raceme. 



— 6. Portion of a raceme, showing the proliferous state in which it is not 



unfrequently found. The two last magnified. 



Sargassum dumosum. 



Fig. 1. Portion of a branch. 



— 2. Leaf and raceme. 



— 3. Vesicles; one of them being supported on an abortive receptacle. 



— 4. Raceme. 2 — 4 magnified. 



