34 HENRIK PRINTZ [1920 



This peculiar alga I have observed on the bark of a tree taken 

 near the ocean, soutli of the Whaling station, Bhiff, in samiple no. 

 28. By means of a sti^ong niagnifying glass it is to be seen ais a 

 velvety coating covering small parts, This coating is fornied by 

 the straight, short and unbranched, nearly parallel, very close-se.t 

 filaments, fastened to the subistratum 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 cylindri- 

 cal cells in a simple row. The oells, all of which are imiform, are 

 broadest in the miiddle of the trichome, where they may attain a 

 breadth of nearly 5 //, becoming gradually narrower towards the 

 eXitremities, especially so towards the apex, where there is a compia- 

 raitively long and narrow apical oell, propagatiing b}^ vivid cross dlivi- 

 sions. The older cells also sornetmies divide, but normally the oell- 

 division is limited to the apical cell only. With the exception of this 

 one, which is several times las long as broad, the cells are equally 

 long, about twice as long as broad. The trichonie is encloised within 

 a fusiform sheath, which, in the miiddle, is nearly 10 u broad and 

 gradually narrowing towards the ends. At the base the sheath is 

 obtusely rounded,towards the top gradually narrowing and decreas- 

 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 witli certainty the multiplication of the alga. 

 In preparations of it there sometimes occur trichom-fragments, and 

 it is probable that theise serve as homiogones. 



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 

 morphologioally particularly adapted to the «tufted growth» men- 

 tioned by Fritsch, 1. c. 1907, p. 210, a growth-form of the bluijsh- 

 green aérial algae frequently to be met with in damp, tropical 

 regions. 



Dactylococcopsis rhaphidioides Hansg., Syn.Gen. subgen. Myx. 

 in Not. 1888, p. 590. 



Of tilis species I have found Iwo 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 oells is 



