THE FRESHWATER ALGÆ OF CEYLON. 161 
rectis, spinis divergentibus acutis tribus ad marginem lateralem unumquemque 
regulariter dispositis, ea infima breviore, in centro granulo instructs; a vertice 
visse oblongo-elliptieze, spina singula ad polum unumquemque, granulo prominenti 
singulo ad medium utrobique ; a latere vise globose. 
Long. sine spin. 92, cum spin. 117 u; lat. sine spin. 7:8 u, cum spin. 10:54; lat. isthm. 
2:14; crass. 5°1 p. 
Hab. Paddyfields, Heneratgodha. 
This minute Yanthidium is readily distinguished from any other species of the genus. 
The only plant approaching it is Arthrodesmus ineptus (— Xanthidium ineptum, W. B. 
Turn. in K. Sv. Vet.-Akad. Handl. 1893, xxv. no. 5, p. 101, t. 12. fig. 21) ; but in the latter 
species the semicells are more elliptic, the spines are irregularly disposed and less 
divergent, and the semicells are devoid of a central protuberance. This last character 
shows that Turner was wrong in placing his plant in the genus XYanthidium. 
144. XANTHIDIUM BENGALICUM, W. B. Turn. in K. Sv. Vet.-Akad. Handl. xxv. no. 5, 1893, 
p. 100, t. 12. fig. 32. 
Long. sine spin. 49 u, cum spin. 77 4; lat. sine spin. 48 4, cum spin. 80; lat. isthm. 
134; crass. 26 nu. 
Hab. With the preceding species. 
145. XANTHIDIUM HASTIFERUM, W. B. Turn. in Journ. Roy. Mier. Soc. 1885, p. 938, t. 15. 
fig. 20. X. antilopewm, Kuetz., var. angulatum, Josh. in Journ. Linn. Soc., Bot. 
xxi. 1886, p. 643, t. 24. fig. 16. 
Var. JAVANICUM, W. B. Turn. in K. Sv. Vet.-Akad. Handl. xxv. no. 5, 1893, p. 100. 
X. antilopeum, Kuetz., forma javanica, Nordst., 1880. 
Long. sine spin. 37 4, cum spin. 58; lat. sine spin. 365-40 u, cum spin. (äu: lat. 
isthm. 9'5 u. 
Hab. With the preceding species. 
In all the specimens examined the spines were very long and delicate, and the sinus 
was distinctly closed, the latter feature being absent from both the figures of Turner 
and Nordstedt. 
Genus COSMARIUM, Corda. 
146. COSMARIUM NyMANNIANUM, Grun. in Rabenh. Flor. Europ. Algar. iii. 1868, p. 166 ; 
Lund. in Act. R. Soc. Scient. Upsala, ser. 3, viii. 1871, p. 36, t. 3. fig. 1. 
Hab. Paddyfields, Heneratgodha. Paddyfield between Kosgoda and Urahaighasma- 
hendai. 
147. Cosmartum Hamuert, Reinsch, in Abhandl. naturhistor. Gesellseh. Nürnberg, 
1866, p. 111, t. 10. fig. 1. C. homalodermum, Nordst. in Ofvers. K. Sv. Vet.-Akad. 
Fórh. 1875, no. 6, p. 18, t. 6. fig. 4. 
Forma. — 
