yellowish-brown, firm, lamellose when old. Contents granulose, refringent. Heterocyst oblongo-rectangular, about 10m long.
As mentioned above, of the Cohort Trichophorecs, in Lahore only Rivularia bullata Berk. (De Toni, I.e. p. 660) has been found as yet. It forms hemispherical, Iobed, gelatinous fronds on damp soil by the river-side. Trichomes 6-8/* thick, bluish-green, a little constricted at the joints, thinned out intoPa hyaline point at the apex. Heterocyst globose, 6-8/x thick. See Fig. 6.
Perennations. In this connection, a few observations might very well be recorded. Terrestrial forms, such as Gleocapsa majus, Nostoc commune, Phormidium Hansgirgi, Tolypothrix byssoidea, Toly- pothrix arenophila, generally tide over the unfavourable time by enclosing themselves in their sheaths, which often become much thicker and sometimes lamellose, and take on a yellowish-brown colour. On the return of favourable conditions they come out of the sheath, and multiply.
Resting spores have been very clearly seen in Tolypothrix distorta in all the stages of development. Generally a number of cells, about four, fuse together by the absorption of the intervening cell- walls and swell up. The contents take on a separate wall, which becomes firm and yellowish-brown. Many spores are formed in a chain-like series. They are oblong in shape, and 18-21/* by 11-13/u. in size. Germination of these spores has not been observed as yet. See Fig. 7.
CONCLUSION. The species of the Blue green Algae, described above, occur quite commonly in Lahore, but in addition to these» there are a few others, which are met with only occasionally ; and for that reason have not been yet identified or studied properly.
Explanation of Plate III.
Fig* 1. A small portion of Oscillator ia princeps. (x500).
Fig. 2. A filament of Oscillator ia terebriformis. (x 1000).
Fig. 3. A portion of Phormidium ladinianum. (x600).
Fig. 4. A portion of Phormidium Hansgirgi. (x666).
Fig. 5. A portion of Phormidium Moerlianum. ( x 666).
Fig. 6. Two filaments of Bivularia bullata. (x 1000).
Fig. 7. A portion of a filament of Tolypothrix distorta, forming resting spores, (x 500).
