The Sub-family Schizotrickea is represented by Microcoleus vaginatus Gam. (De Toni, p. 374 ; Cooke, p. 258, pi. 99, fig. 2, under M. tcrrestris Deson) which lives commonly on damp mud, such as that in lawns, flower-pots, and around ponds and ditches. Trichomes long, collected in filiform, tortuous fascicles, enclosed in a common mucous sheath, from the apes of which they come out in a penicillate manner. Dissepiments granulated, Fascicles 75-80/* thick ; trichomes 4-5/* thick.
The family Nostocacecd is represented by Nostoc commune Vauch. (De Toni, I. c. p. 404 ; Cooke, I. c. p. 231, pi. 91, figs. 4-7) and Cylindrospermum majus Kuetz. The former is found in large abundance in damp soil, even on lawns after a little rain or watering. Colonies are at first globose and resemble Botrydium, then they expand and become more or less irregular, but still keeping the outer membrane intact. Trichomes flexuous, loosely intricate ; joints spherical, uniform about 5/* thick. Heterocysts globose, 7/* thick.
Cylindrospermum majus Knetz. (De Toni, I. c. p. 424) is occasionally met with, forming a bluish-green, thin expanded stratum on damp mud. Trichomes 4-5/^ thick. Heterocysts oblong, 6-8/* thick. Spore cylindrical, 10/* wide, 20-25/* long.
From the Sub-family Scytonemacea, three species of Tolypothrix are commonly met with in Lahore. Tolypothrix distorta Euetz. (De Toni, p. 541 ; Cooke, p. 268, pi. 108, fig. 2) is very abundant in stagnant or very slowly running water, such as the broad water- courses of the Shalamar Gardens. It generally forms a very much expanded bluish -green stratum on broad floating, half -decayed leaves, such as those of the water lily. Trichomes and pseudo-branches loosely interwoven, 8-11/* thick ; joints sometimes indistinct. Sheath membranous, thin, sometimes inflated at the base of the branch, hyaline, yellowish- brown when old. Heterocysts 8-9/* thick, and 12-14/* long.
Tolypothriz byssoidea Kirchn. (De Toni, B.C. p. 551) forms a dark brownish stratum on the trunks of trees such as those of Acacia modesta, and is generally associated with Phormidlum ladmlanwm and Phormidlum Hansglrgi. Trichomes 9-11/* thick, with irregular pseudo-branches, torulose. Sheath thin, yellow or brown, fragile, tubular. Heterocysts oblong, about 16/* long.
Tolypothrix arenophila West (De Toni, I. c. p. 554) lives on damp coarse mud, such as that in lawns or around ponds and ditches. At first it forms small circular bluish-green, shiny patches, which expand later on. By coalition of several such patches a very extensive stratum is produced. Trichomos flexuous and contorted, densely intricate, about 6/* thick, with few pseudo-branches. Sheath thick,
