Dr. Greville on some new species of Sargassum. 483 



less oblong-acuminate outline. Towards the base, the branches 

 appear to be frequently in pairs ; two being given off near to- 

 gether, then after a longer space two more and so on, but this 

 character is gradually lost, and the upper branches become irre- 

 gularly alternate, at intervals of half an inch or more. These 

 branches produce the fruit-bearing ramuli at intervals of a few 

 lines; they are an inch or more in length next the stem, and 

 diminish insensibly to the extremity of the branch. Leaves : 

 those arising from the stem close to the root, ovate-oblong, sub- 

 sessile ; those on the branches about an inch in length, linear- 

 lanceolate, becoming gradually shorter and narrower towards the 

 extremity, deeply and irregularly dentato-serrate, furnished with 

 minute pores and a narrow nerve which is very faint towards the 

 apex. Vesicles numerous, from the size of a large pin^s head to 

 that of hemp -seed, subglobose, often slightly elliptical, on stalks 

 a line or more in length ; but these stalks have a frequent ten- 

 dency to pass into leaves ; in some specimens nearly all are foli- 

 aceous, and several lines long, the vesicles themselves being then 

 more or less elliptical, winged, and often apiculate. Receptacles 

 1 or 2 lines long, linear-cuneate, compressed, sometimes subtri- 

 quetrous, bristling at the lateral and terminal margin with large, 

 very acute teeth. Generally the raceme is composed of but few 

 simple receptacles, but occasionally they are proliferous, as shown 

 in the plate. The terminal receptacle is often large and the 

 lateral or lower ones very small. Colour a dark reddish brown 

 when dry ; a rich yellow-brown in transmitted light. Substance 

 somewhat membranaceous and translucent, but rigid in the dry 

 state. 



This species, to which 1 at one time attached the provisional 

 name of ermaceum, is distinguished for its beautiful foliage and 

 the very slender branches, which indeed are scarcely thicker than 

 a hog^s bristle. The light and graceful character of the whole 

 plant is increased by the dentation of the leaves, which is some- 

 times so marked even to the naked eye, as to give them a laci- 

 niate character. 



9. Sargassum dumosum (nob.); caule subplano, distiche ramose; 

 foliis lineari-lanceolatis, uninerviis, inferne prsecipue attenuatis, 

 superne plus minusve dentatis ; vesiculis ellipticis, petiolatis, pe- 

 tiolis elongatis, dilatatis, foliaceis ; receptaculis axillaribus, clava- 

 tis, subcompressis, dentatis, racemosis. 



Hah. in mari Peninsulee Indise Orientalis ; Wight. 



Root I have not seen, the only specimen in my possession 

 being about a foot of the upper portion of the plant. In this, 

 the stem (?) is about a line broad, flat or nearly so, and giving off 

 branches 5 or 6 inches in length in a distichous manner, at in- 



Ann. ^ Mag. N. Hist. Ser. 2. Vol\\. 30 



