30 F. EH. FRITSCH. 
This Alea, about the determination of which I am not quite certain, formed a 
stratum together with Phormidium angustissomum W. and G. 8. West. The filaments 
were very densely and irregularly entangled, and many of them showed a complete 
spiral coiling of several turns (figs. 74, 75); others, however, were merely flexuous 
or even straight for a considerable distance, such filaments being on the whole in 
the majority. The sheath was prominent, mostly fitting very close, although 
oecasionally a little off-standing. The cell-contents were pale blue-green and often 
vacuolar or provided with scattered granules of moderate size. In no case could a 
reeular placing of granules with reference to the septa be recognised. Gomont himself, 
however, queries this part of the diagnosis of L. lagerheimi, and his figures certainly 
fail to show anything of the kind. The cells of the trichomes were generally slightly 
longer than broad (fig. 78). The apex of the trichome appears to be rounded and 
obtuse. 
Genus PHorMIpiIuMm Kiitz. 
37. PHORMIDIUM AUTUMNALE. 
(Piece poe. O43) 
Phormidium autumnale (Ag.) Gom., tom. cit., pp. 187-190, Pl. V., figs. 23, 24. 
Diam. trich. = 3°8-4°5 p; long. cell. = 3°8 pw. 
Hab.—Frveshwater pond, Granite Harbour, January 20th, 1902. 
The cells were sometimes a trifle longer than broad; the septa were marked by 
a prominent double row of granules. The apex of the filament was not always 
prominently attenuated (fig. 53), but was markedly capitate, the apical cell being 
depressed-conical. 
This species was not as abundant in my material as in that examined by 
Messrs. West (ef. op. cit., p. 291); in the locality above named it, however, evidently 
formed extensive pure strata. 
38. PHORMIDIUM LAMINOSUM. 
Phormidium laminosum Gomont, Essai de classif. d. Nostoc. homocystées, Journ. de Bot., iv. (1890), p. 355 ; 
Monogr. Oscill., tom. cit., pp. 167-168, Pl. IV., figs. 21, 22. 
Diam. trich. = 1-1°5 pw; cellulis saepe clongatis (usque ad 5 jp). 
Hab.—Gap pond, Winter Harbour. 
The cells were frequently much elongated, but apart from that the specimens 
agreed well with Gomont’s description. The inconspicuous septa were generally 
provided only with two granules, one on either side ; according to Gomont there are 
four, but his figures fail to show more than two. The bulk of Phormidium from the 
Gap pond appears to belong to this species. 
