SYSTEMATIC*[1] Of the two orders of the Myxophycea, namely the Coccogoneaz and the Hormogonece, the latter has been much more studied by the writer. Amongst the former, Chroococcus turgidus Kuetz, (Cooke, 7. c. p. 204, pi. 83, fig. 2) is very commonly found for the most part of the year, generally sticking to the submerged walls or the floating masses of decaying vegetable matter in stagnant ponds or ditches. It is about 20/* thickness, and is often seen to be dividing into two, or rarely into four.
Gloeocapsa polydermatica Kuetz., is very common amongst the grass on lawns after a little rain or watering. It forms a thick, green layer when moist. Individual cells have a hyaline lamellose membrane, and are about 5/u. thick. When dry, the stratum becomes greenish-brown, the membrane of the individual cells also taking on that colour.
Clathrocystis aeruginosa Henf. (De Toni, I.e. p. 94: Cooke, I.e. p. 212 pi. 86, fig. 7) forms a bright green scum on stagnant water, generally where the water is full of waste organic matter such as the Duck Pond in the Zoo. Fronds of various sizes and of various shapes are commonly met with at the same time. Young fronds seem to be solid, but as they grow old they become hollow, and finally clathrate.
Two or three species of Merismopedia are fairly common, with their families freely floating in stagnant water, or sometimes sticking to floating masses of decaying vegetable matter.
Of the second orders Hormogoneai, the Cohort Psilonematea is very well represented in Lahore, while the Cohort Trichophorea is as yet found to be represented only by Eivularia bullata Berk. Of the former, the three families, Oscillatoriacece, Nostocacece and Scytonemacece have been found to be fairly well represented, while no plant of the Stigonemacece has as yet been discovered.
Oscillatoria princeps Vauch. (De Toni, /. c. p. 150) is the thickest species of the genus yet found. It generally occurs in dirty drains, carrying off water from road-side water-pipes. Stratum dark green, first attached to the mud and then floating. Trichomes straight, rigid, yellowish-green, about 36/* thick. See Fig. 1.
Oscillatoria tenuis Ag. (De Toni, I. c. p. 166 ; Cooke, /. c. p. 249; pi. 96, fig. 8) is the commonest Oscillatoria of Lahore, found generally in dirty draius and in places constantly wetted, such as in mud
- ↑ * The classification of the Myxophycese followed in this paper is taken from J. B. De Toni's 'Sylloge Algarum', Vol. V., (1907). The species have been identified from descriptions in that book or from descriptions and figures given in M. C. Cooke's British Fresh-water Algae (1882— 1884). Exact references are given after each species.
