34 HENRIK PRINTZ [1920 
This peculiar alga I have observed on the bark of a tree taken 
near the ocean, south of the Whaling station, Bluff, in sample no. 
28. By means of a strong magnifying glass it iis to be seen as a 
velvety coating covering small parts. This coating is formed by 
the straight, short and unbranched, nearly parallel, very close-set 
filaments, fastened to the substratum with one end, while the free 
one is projecting. 
The filaments are straight, or at the base sometimes slightly 
curved and ascending, and are easily loosened from the substratum. 
The trichomes themselves are short, and consist of 15—20 eylindri- 
cal cells in å simple row. The cells, all of which are uniform, are 
broadest in the middle of the trichome, where they may attain a 
breadth of nearly 5 u, becoming gradually narrower towards the 
extremities, especially so towards the apex, where there is a compa- 
ratively long and narrow apical cell, propagating by vivid cross divi- 
sions. The older cells also sometimes divide, but normally the cell- 
division is limited to the apical cell only. With the exception of this 
one, Which is several times as long as broad, the cells are equally 
long, about twice as long as broad. The trichome is enclosed within 
a fusiform sheath, which, in the middle, is nearly 10 ps broad and 
gradually narrowing towards the ends./ At the base the sheath is 
obtusely rounded,towards the top gradually narrowing and deereas- 
ing, but never drawn out into hair-like points above the apical cell. 
The sheath is unstratified and colourless, at times, in older speci- 
mens, slightly greyish-violet. In the material at my disposal I have 
not been able to find with certainty the multiplication of the alga. 
In preparations of it there sometimes oceur trichom-fragments, and 
it is probable that these serve as hormogones. 
With regard to affinities, our alga must be classed among the 
Oscillatoriaceae, where it has its nearest relations among genera 
distinguished by a thick, solid sheath. 
This genus presents an evident example of an alga which is 
morphologically particularly adapted to the «tufted growth» men- 
tioned by Frritscn, 1. €. 1907, p. 210, a growth-form of the bluish- 
green aérial algae frequently to be met with in damp, tropieal 
regions. 
Dactylococcopsis rhaphidioides HAansa., Syn. Gen. subgen. Myx. 
in Not. 1888, p. 590. 
Of this species I have found two different forms. One I have 
observed on trunks of trees, collected in the environs of Durban, at 
Bluff, south of the Whaling station (no. 28), and its is distinguished 
by nearly straight or only sligtly curved, equally broad cells, nar- 
rowed and acuminate towards the extremities. Often one end of 
the cells is straight, the other slightly curved, or the cells nearly 
S-formed, or slightly spirally twisted. The breadth of the cells is 
