338 MR. S. L. GHOSE ON A COLLECTION OF 
Faeroes, 1901, p. 208) has recorded O. limosa up to 33 a thick, but unfortun- 
ately he does not figure his form. There are two other reasons which induce 
me to refer this alga to the species princeps rather than to limosa. Firstly, 
among Prof. G. S. West's figures of O. princeps at the British Museum 
(Natural History), London, there are two in which the apex is quite 
straight as in the alga under discussion, Secondly, filaments are sometimes 
seen in my material, which show a slight curvature and attenuation at the 
apex (Pl. 81. fig. 2,b). 
12. OSCILLATORIA TENUIS, Agardh; Gom., Monog. Oscill. 1893, p. 240, 
pl. 7. figs. 2,3. 
Diam. cell.= 5-9 a. 
Hab. Lahore, commonly found in dirty drains and in places constantly wet, 
such as on mud round water-pipes or wells ; throughout the year. 
13. PHORMIDIUM AUTUMNALE (Agardh), Gom. tom. cit. p. 207, pl. 5. 
figs. 23, 24. 
Diam. cell.— 4-7 a. 
Hab. Lahore, in drains or on moist ground ; most of the year. 
14. PHORMIDIUM TRUNCICOLA, sp. n. (PI. 31. fig. 2.) 
Strato valde expanso, membranaceo, flavo-viride vel æruginoso ; vaginis 
ditHuentis, fibrosis ; trichomatibus 6-8 u crassis, subparallelis, ad genicula 
distincte constrietis; articulis fere tam longis quam latis ; apicibus attenuatis; 
calyptra nulla ; contentu in media cellularum densiore, 
Hab. Lahore, growing on trunks of Acacia modesta, associated with other 
blue-green algæ ; July—October. 
This species is like P. fragile (Menegh.), Gom., but differs from it in its 
peculiar habitat, its much broader filaments, and in the nature of the stratum. 
15, ARTHROSPIRA PLATENSIS (Nordst.), Gom. tom. cit. p. 247, pl. 7. fig. 27. 
Diam. spir. = 25-30 a; dist. inter anfractibus = 40-55 u ; diam. cell. = 6-8 a. 
flab. Lahore, free-floating in stagnant water, generally associated with 
Clathrocystis wruginosa ; most of the year. 
16. ARTHROSPIRA SPIRULINOIDES, sp. n. (Pl. 31. fig. 4.) 
Trichomatibus ærugineis ; articulis haud constrictis, 5-6 y latis, 4-12 u 
longis, protoplasmate subtiliter granuloso ; spiris densis anfractibus contiguis, 
rectis vel leviter flexilibus, usque ad 60 y longis ; diametro 12-15 a. 
Hab. Lahore, in a dirty stagnant rain-water pool, free-floating ; October, 
1918. 
This alga looks very much like a Spirulina, such as S. subsalsa, Oerst., but 
because it shows some clear dissepiments, it cannot be referred to that 
unicellular genus. 
