— - 
THE FRESHWATER ALGJE OF CEYLON. 189 
always retained its characters, we thought it advisable to regard it as a distinct species. 
It differs from Delponte's species in its relatively smaller body, in the prominent constriction 
above the base of the semicells, in the more acute dentation, and in the prominent smooth 
apex. The vertical view also differs in its concave sides and more graceful processes. 
From Staurastrum Pseudosebaldi, Wille, it is easily distinguished by the nature of the 
processes, which possess very prominent teeth only on the upper and lower margins, thus 
appearing almost smooth in vertical view. The nature of the base of the semicells 
and other characters also distinguish it from S. Pseudosebaldi. 
Var. ELEGANS, var. n. (Pl. 22. fig. 17.) Var. minor, processibus longioribus. 
Long. 384; lat. cum proc. 59 4; lat. isthm. 8:5 y. 
Hab. Paddyfield between Kosgoda and Urahaighasmahendai. 
Compare with S. longiradiatum, West & G. S. West. 
261. STAURASTRUM CYCLACANTHUM, sp. n. (Pl. 92, fig. 18.) S. subparvum, 13-plo 
latius quam longum (eum processibus), modice constrictum ; semicellule latissime 
obeuneatz, angulis superioribus in processus longos leviter incurvatos productis, 
marginibus lateralibus semicellularum acute binodosis, marginibus inferioribus 
processuum dentibus acutis 4 instructis, marginibus superioribus processuum in 
parte proxima spinis profunde bifurcatis 2 et in parte distante dentibus acutis 
2 munitis, apicibus processuum cum spinis parvis 4, apicibus semicellularum 
levissime convexis cum verrucis trispinatis (a fronte visse 3—4 indistinetis), trans 
nodum basalem semicellularum eum annulo granulorum interrupt»; a vertice visse 
triangulares, lateribus glabris leviter concavis, angulis in processus longos subundu- 
latos productis, in centro cum annulo verrucarum trispinatarum 6, ad basin 
processus uniuscujusque spinis bifurcatis 2. 
Long. 30-31 »; lat. cum proc. 44-53 4; lat. isthm. 8 u. 
Hab. Paddyfields Heneratgodha. 
After some consideration we have decided to describe this plant as a new species, as it 
retains its characters quite constantly, and does not agree in the arrangement of its 
spines, warts, &c. with any of the described species to which it is allied. Perhaps its 
nearest relative is S. floriferum, West & G. S. West (in Trans. Linn. Soc., ser. 2, Bot. v. 
1896, p. 267, t. 18. fig. 1) a species which, up to the present, is only known from 
N. America. It differs from this plant, however, in the nodose lateral margins of the 
semicells and in the teeth on the inferior margins of the processes, as well as in the two 
prominent bifurcate spines on the basal portion of the superior margin of each process. 
The processes of S. cyclacanthwm are incurved, whereas those of S. floriferum are straight, 
and the apices of the processes of the former are furnished with four short spines, 
whereas those of the latter are provided with only three spines; moreover, the node at 
the base of each semicell of S. cyclacanthum is provided with an interrupted ring of 
granules. Both these species agree in the possession of an apical ring of six warts, but 
in S. cyclacanthum each wart is furnished with three spines, whereas in A. floriferum 
these spines are reduced to mere denticulations. - 
D2 
