156 MESSRS. W. WEST AND G. S. WEST ON 
Turp. 1820. Cosmarium Aitchisonii, as figured by Turner in K. Sv. Vet.-Akad. 
Handl. 1893, xxv. no. 5, t. 8. fig. 54 a, b (a is oblique). 
Hab. Among Spirogyra sp. in fast-running stream, Peradeniya. In stream and 
in ponds, Victoria Park, Colombo. Paddyfield between Kosgoda and Urahaighas- 
mahendai. 
Forma HIANS, West, in Journ. Linn. Soc., Bot. xxix. 1892, p. 140, t. 20. fig. 14. 
Hab. Paddyfield between Kosgoda and Urahaighasmahendai. 
125. EUASTRUM INSULARE, Roy, in Scot. Naturalist, vii. 1883, p. 40. E. binale, var. insu- 
lare, Wittr. in Bih. till K. Sv. Vet.-Akad. Handl. i. no. 1, p. 49, t. 4. fig. 7. 
Long. 17:5 w; lat. 11.5 p; lat. isthm. 3:3 p. 
Hab, Paddyfields, Heneratgodha. Paddyfield between Kosgoda and Urahaighas- 
mahendai. Stream, Victoria Park, Colombo. 
126. EvastruM VALIDUM, West & G. S. West, in Trans. Linn. Soc., Bot. ser. 2, v. 1896, 
p. 245, t. 14. figs. 32, 33. 
Long. 265 w; lat. 19 u; lat. apie. 13:5 p; lat. isthm. 4°44; crass. 10 p. 
Hab. Paddyfields, Heneratgodha. 
A little smaller, otherwise exactly like the American forms of the species. 
127. EUASTRUM LIGATUM, sp.n. (Pl.19.figs. 18,19.) E. perminutum, subduplo longius 
quam latum, profundissime constrictum, sinu acuto et aperto; semicellulæ truncato- 
pyramidatz, lateribus profunde retusis, angulis inferioribus et superioribus acute 
rotundatis, apicibus latis convexis et in medio retuso-emarginatis; a latere visse 
truncato-ovatz, sub apice constrictze ; a vertice visse elliptic; membrana glabra. 
Long. 14°5-15 u; lat. 94-97 p; lat. apic. 72-77 p; lat. isthm. 277-3:2 p; crass. Ou 
Hab, Paddyfields, Heneratgodha. 
At first sight this resembles Spondylosium pulchellum, Arch., and especially the var. 
austriacum, Lütkem. (in Verhandl. d. k. k. zool.-bot. Ges. Wien, 1892, xlii. p. 539, t. 8. 
fig. 1), but on closer examination the difference is at once evident. A. ligatum is relatively 
narrower, the constriction is very much deeper, the sinus is more open, the angles are 
acutely rounded, and the apex is convex and slightly emarginate in the middle. "The 
apices of the cells of Spondylosium pulchellum are absolutely straight, as it is by the 
close application of these flat ends that the cells are joined into long filaments. 
E. ligatum does not occur in a filamentous state, and the side view of the semicells 
shows a marked constriction below the apex, which is not present in Spondylosium 
pulchellum. 
Genus MICRASTERIAS, Ag. 
128. MIcRASTERIAS PINNATIFIDA, Ralfs, Brit. Desm. 1848, p. 77, t. 10. fig. 3. .Euastrum 
pinnatifidum, Kuetz. Sp. Alg. p. 171. 
Hab. Paddyfields, Heneratgodha. 
Pern ea | 
BEE H 
