Dr. Greville on some new species of Sargassum. 255 



narrow-obovate, rounded at the apex, attenuated at the base into 

 a slender and rather long footstalk, often nearly entire, but more 

 generally repando- or even serrato- dentate, furnished with pores, 

 and a nerve which disappears before reaching the summit. Vesi- 

 cles nearly the size of hempseed, subspherical, supported on stalks 

 scarcely a line long. Receptacles a line or more in length, ax- 

 illary, obovate, or oblong, compressed, the margin and apex fur- 

 nished with broad sharp teeth ; frequently the receptacles are 

 proliferous, the whole forming a very irregularly divided raceme, 

 which is sometimes so twisted and curled as to give it the appear- 

 ance of a cluster of minute proliferous leaves. 



From the two imperfect specimens which I possess of this 

 plant, I suspect that it is subject to considerable variation, and 

 my figure and description are given chiefly with a view of affording 

 algologists a memorandum for its more accurate investigation. 

 On one of my specimens several of the leaves are converted into 

 vesicles, which are supported on stalks 2 lines long resembling 

 the lower part of the leaf ; these are also winged and apiculate. 



17. Sargassum divaricatum (nob.) ; caule angulato ; foliis linearibus, 

 acuminatis, breviter petiolatis, uninervibus, subintegerrimis ; vesi- 

 culis numerosis, sphsericis, petiolatis, petiolis planis, dilatatis ; 

 receptaculis cylindraceis, filiformibus, divaricato-dichotomis. 



Wight in herb. no. 7. 



Hah. in mari Peninsulse Indise Orientalis ; Wight. 



Root I have not seen. Entire plant probably a foot or more 

 in length. Stem nearly as thick as a crow-quill, giving off 

 spreading branches at short intervals 4 to 6 inches long, which 

 are clothed with numerous short ramuli and leaves, so as to give 

 the whole plant a bushy appearance. Leaves somewhat more 

 than an inch in length, a line or more broad, more or less 

 acuminate, entire, or rarely obscurely subdentate, shortly petio- 

 late, furnished with a nerve and pores. Vesicles spherical, smaller 

 than hempseed, on little flat dilated petioles about a line long ; 

 sometimes they are margined, and occasionally on longer stalks 

 resembling an abbreviated leaf, and apiculate. Receptacles fili- 

 form, cylindraceous, subdichotomously divided, the segments 

 spreading, the whole forming axillary tufts, often 3 or 4 lines in 

 length. Colour reddish brown, that of the receptacles black. 

 Substance cartilaginous. 



A well-marked species, the receptacles separating it at once 

 from its congeners. When luxuriant the three or four tufts on 

 a ramulus seem to form one mass, and to the naked eye suggest 

 the idea of a little parasitic Gigartina, and is by no means unlike 

 dwarf specimens of Gymnogonijrus Griffithsice, Mart. Sometimes 

 the receptacles are less abundant and conspicuous, having fewer 



