164. MESSRS. W. WEST AND G. S. WEST ON 
157. CosMARIUM OBSOLETUM, Reinsch, in Abhandl. naturhist. Gesellsch. Nürnberg, 
iii. 1866, p. 110, t. 9. fig. 5. 
Long. 41-67 „u; lat. 50-76 u; lat. isthm. 22-31 u. 
Hab. Paddyfields, Heneratgodha.  Paddyfield between Kosgoda and Urahaighas- 
mahendai. 
The specimens were exactly like those from Singapore (cf. Journ. Linn. Soc., Bot. 
xxxiii. 1897, p. 164). 
158. CosMARIUM PSEUDOSCENEDESMUS, sp. n. (Pl.20.fig. 34.) C. subparvum, circiter 
1i-plo latius quam longum, profundissime constrictum, sinu angusto-lineari extremo 
leviter ampliato; semicellulee depresso-semielliptice, angulis basalibus rotundatis, 
apicibus subtruncatis ; a vertice vise anguste ellipticze; a latere visse circulares; 
membrana sparsissime scrobieulato-punctata. 
Long. 30 „u; lat. 49 4; lat. isthm. 12 u; crass. 15 y. 
Hab. Paddyfields, Heneratgodha. 
This species is nearest to C. Scenedesmus, Delp., and especially its var. dorsitruncatum, 
Nordst. It can be distinguished, however, from all forms of C. Scenedesmus by 
its more depressed and flattened semicells, by its very much deeper constriction, and 
the extremely narrow closed sinus. "The vertical view is also more narrowly elliptical, 
and the cell-wall exhibits peculiar scrobiculations somewhat distantly placed from each 
other. 
159. CosMARIUM DEPRESSUM, Lund. in Act. R. Soc. Scient. Upsala, ser. 3, viii. 1871, 
p.98. Euastrum depressum, Naeg. Gatt. einzell. Alg. p. 114, t. 7 c. fig. 2. Forma 
cellulis in medio apicum levissime et minute retusis. 
Long. 26 »; lat. 31:5 »; lat. isthm. 6'5 u; crass. 12 p. 
Hab. With the preceding species. 
160. CosMARIUM TITHOPHORUM, Nordst. in Act. Univ. Lund. xvi. 1880, p. 6, t. 16. 
fig. 6. 
Var. DEPRESSUM, var. n. (Pl. 20. fig. 29.) Var. paullo minor, semicellulis leviter 
depressis. 
Long. 18:8-19 u; lat. 20:5-22 p; lat. isthm. 46 p; crass. 13974 p. 
Hab. With the preceding species. 
C. Onychonema, Racib. (in Flora, lxxxi. 1895, Heft 1, p. 33, t. 4. fig. 12), appears 
to be an abnormal form of C. tithophorum ; it is exactly the same size as the 
var. depressum, and only differs in the excentrie position of the central protuberances. 
161. CosMAnIUM TINCTUM, Ralfs, Brit. Desm. 1848, p. 95, t. 32. fig. 7. 
Hab. Paddyfields, Heneratgodha.  Paddyfield between Kosgoda and Urahaighas- 
mahendai. 
