THE FRESHWATER ALGÆ OF CEYLON. 155 
umbonatum), but we are unable to see any reason for this, as the outward form and central 
elevation are exactly similar to those of typical Æ. rostratum, Baltes 
121. EvasrruM LoBULATUM, Bréb. in Mém. Soc. Sci. Nat. Cherbourg, iv. 1856, p. 124, 
t. 1. fig. 4; West & G. S. West, in Journ. Bot. xxxviii. 1900, p. 290. Æ. erosum, 
Lund., var. notabile, West, in Journ. Roy. Mier, Soc. 1892, p. 723, t. 9. fig. 17. 
Var. TROPICUM, var. n. (Pl. 19. fig. 13.) Var. angulis basalibus subrectangularibus 
(lateribus angulorum basalium subdivergentibus) leviter retusis, in centro semi- 
cellularum eum tumore prominenti quadrigranulato. 
Long. 304; lat. 184; lat. apic. semicell. 11,4; lat. isthm. 4'5 u; crass. 14 p. 
Hab. With the preceding species. 
This is very similar to a form figured by Schmidle as Æ. elegans forma (in Engler's 
Bot. Jahrbüch. xxvi. 1898, t. 2. fig. 36). 
122. EUASTRUM DENTICULATUM, F. Gay, in Bull. Soc. Bot. France, xxxi. 1884, p. 335. 
E. binale, var. denticulatum, Kirchn. in Cohn's Kryptog. Flor. Schlesien, 1878, p. 159. 
Hab. Stream, Victoria Park, Colombo. In artificial tank, Peradeniya. Pool in glen 
by roadside, near Bandarawella (altit. 4000-5000 ft.). Paddyfield between Kosgoda and 
Urahaighasmadendai. 
Forma cellulis paullo latioribus, angulis basalibus semicellularum rectangularibus. 
Long. 354; lat. 27 4; lat. isthm. 5 4. (PI. 20. fig. 16.) 
Hab. Paddyfield between Kosgoda and Urahaighasmahendai. 
123, EUASTRUM BASICHONDRUM, sp. n. (Pl.20.figs. 14, 15.) E minutum, 14-plo longius 
quam latum, profunde constrictum, sinu angusto-lineari extremo ampliato; semi- 
cellule oblongo-hexagon:e, angulis inferioribus subrectangularibus, lateribus inferi- 
oribus subrectis et subdivergentibus, lateribus superioribus levissime concavis et 
incrassatis, apicibus latis leviter retuso-emarginatis, granulo magno supra et juxta 
isthmum, granulo infra et juxta medium apicis, et scrobiculo singulo intra marginem 
ad medium lateris superioris uniuscujusque instruct ; a latere vise truncato-ovate, 
ad basin utrobique granulo magno instructz ; a vertice visse elliptice. 
Long. 21-244; lat. 15-18 x; lat. apic. 105-12 4; lat. isthm. 3 7-481; crass. 9°7 a. 
Hab. Paddyfields, Heneratgodha. 
The form of the cell, the prominent granules above the isthmus, and those below the 
middle of the apex of each semicell are characteristic. The peculiarly thickened upper 
portions of the lateral margins, and the scrobiculations within them, are also features 
whieh enable this plant to be distinguished from other small species of the genus. 
E. validum, West & G. S. West, is the only other small species of Euastrum which 
possesses a granule on each side of the isthmus. It may also be compared with 
E. crassangulatum, Borgesen. 
194. EUASTRUM BINALE, Ehrenb. in Bericht Verh. Akad. Wissensch. Berlin, 1840, 
pp. 208-9; Ralfs, Brit. Desm. 1848, p. 90, t. 14. fig. 8. Heterocarpella binalis, 
SECOND SERIES.—BOTANY, VOL. VI. Z 
