BLUE-GREEN ALGAE FROM LAHORE AND SIMLA. 399 
layer, which becomes very slimy and conspicuous after the rains, and consists 
of Phormidium truncicolum, sp. n., Lyngbya truncicola, sp. n., and Tolypothrix 
campylonemoides, sp. n., in rapid growth and multiplication. Hormogones 
are formed abundantly in the wet season, and, as the stratum dries, these 
produce mucilaginous sheaths, which slowly get thicker, firm, and coloured. 
The stratum then becomes thin and papery, and may ultimately peel off the 
trunk of the tree. 
The type form of Lyngbya circumereta is planktonic, while the new variety 
described below forms a gelatinous stratum on wet soil. Similarly, Anabuna 
gelatinicola, sp. n., whose nearest allies (4. spiroides, Klebahn., and A. Flos- 
aquae, Breb.) are both planktonic, occurs as a gelatinous stratum on moist 
bare ground. It is curious that both Lyngbya cireumcreta var. gelatinicola, 
and Anabenu gelatinicola, sp. n., have spiral trichomes with many broad and 
closely arranged coils, thus differing from their free-floating allies. 
The blue-green alge of Lahore are exposed to the most extreme conditions 
during the months of May and June, when it is very hot and dry. At this 
time the cells or filaments are either enveloped by thick and coloured sheaths 
(as in species of Glwocapsa, Campylonema, and Lyngbya) or they produce 
resting spores (as in (læocapsa rupestris, species of Cylindrospermum, 
Aulosira, Nostoc, Anabwna, and Rivularia). The threads of the subaerial 
species of Oscillatoria seem to be able to retain their vitality without the help 
of a sheath or spores. As soon as these dried filaments obtain access to 
moisture they form hormogones and multiply. . 
In Simla, where the rains occur earlier and are more frequent, slimy strata 
consisting mainly of species of Glwocapsa and Anabwna are formed on rocks 
throughout the months of July, August, and September, but as soon as the 
rains stop rapid spore-formation takes place. Thus, most of the Cylindro- 
spermum licheniforme found in October was in spore condition, and vegetative 
stages could only be secured with great difficulty. Similarly, Anabena 
variabilis was forming spores abundantly even in August. It seems, there- 
fore, that spore-formation takes place earlier in Simla than in Lahore. This 
is probably to be ascribed to two causes, namely : first, the absence of 
standing water, the plants growing vegetatively on the rocks as long as rains 
last, and secondly, the severe winter, which follows the rainy season, and 
during which there is always a snowfall. Before the rains the rocks of Simla 
are quite bare of any algæ, but species of Oscillatoria and Glwocapsa may 
be found growing in drains and round water-taps, ete. Thus in Lahore 
the vegetative season for most Myxophyceæ seems to be between August 
and February, and the fruiting season between February and April, while 
in Simla the vegetative season is from June to October, and the fruiting: 
season from September to November. In Simla the resting season is from 
November to April. 
