THE FRESHWATER ALG OF CEYLON. 135 
49. PENIUM HETEROTAPHRIDIUM, sp.n. (Pl. 18. figs. 3, 4.) P. mediocre, cellulis dia- 
metro pæne 3-plo longioribus, in medio modice et subgradatim constrictis, leviter 
attenuatis polos versus, polis truncato-retusis; membrana scrobiculata, scrobiculis 
prope medium cellularum majoribus et sparsis subregulariter ordinatis, iis polos 
versus minoribus confertis et in seriebus transversis ordinatis; a vertice vis: 
cireulare. 
Zygospora subglobosa, glabra. 
Long. 69-734; lat. 25-29 u; lat. apic. circ. 135-1504; lat. med. 22-244; diam. 
zygosp. 36-40 n. 
Hab. Paddyfields, Heneratgodha. 
The nearest species to this is P. adelochondrum, Elfv., from which it differs in its 
larger size, its greater constriction, its retuse poles, and in the peculiarly scrobiculated 
cell-wall. It may also be compared with P. lagenariovides, Roy, and P. lagenarioides 
var. sydneyense, Racib. 
50. PENIUM VARIOLATUM, West & G. S. West, ‘Welw. Afric. Alg., Journ. Bot. xxxv. 
1897, p. 77, t. 368, fig. 23. 
Forma cellulis paullo brevioribus, apicibus levissime retusis. Long. 2655-2754; 
lat. 8-9 4. (Pl. 18. fig. 10.) 
Hab. Paddyfields, Heneratgodha. 
51. PENIUM INCONSPICUUM, West, in Journ. Roy. Mier. Soc. 1894, p. 4, t. 1. figs. 6, 7. 
Long. 17 u; lat. 5'4 p. 
Hab. Paddyfields, Heneratgodha. 
52. PENIUM SPINOSPERMUM, Joshua, in Journ. Bot. xxiii. 1885, p. 23, t. 254. fig. 10. 
Forma minor. Long. 25-29; lat. 145-1554; diam. zygosp. c. proc. 26-27°5 y. 
(Pl. 18. figs. 8, 9.) 
Hab. Paddyfields, Heneratgodha. 
53. PENIUM NAVICULA, Bréb. in Mém. Soc. Sei. Nat. Cherbourg, iv. 1856, p. 146, t. ii. 
fiv. 37. 
Hab. Paddyfield between Kosgoda and Urahaighasmahendai.  Paddyfields, Henerat- 
godha. Pond, Victoria Park, Colombo. 
54. PENIUM LIBELLULA, Nordst. in Vidensk. Meddel. naturh. Foren. Kjébenhavn, 
1888, p. 184. Closterium Libellula, Focke, Physiolog. Stud. 1847, p. 58, t. 3. 
fig. 99. Penium closterioides, Ralfs, Brit. Desm. 1848, p. 152, t. 31. fig. 4. 
Hab. Paddyfields, Heneratgodha. 
Forma INTERRUPTA, West, in Journ. Roy. Micr. Soc. 1892, p. 721. 
Hab. With the typical plant. 
