28 HENRIK PRINTZ [1920 
gametes escape. Åt times, however, there occur gametangies drawn 
out into å longer or shorter beak, with the opening at the end. (Vide 
pl. VII, fig. 245 and pl. VIII, fig. 253 and 260). This is rare, however, 
and must apparently be regarded as an abnormity. The chromato- 
phore in this species is often seen to contract in a characteristic way, 
on account of the desiccation. For the chromatophore is broadest at 
the cross-walls of the cell, and narrows towards the middle, like an 
hour-glass. PI. VIII, fig. 250 will give an idea of this. 
This species is very common in quite a number of the samples 
examined from Durban, but I have not observed it in any of the 
samples from Saldanha Bay. Ås to its occurrence may be noticed 
that in practically all the samples examined, it is associated 
with a liver-wort and Physolinum monile (nos. 108, 120, 133, 179, 
261, 295) or sometimes with Acanthococcus granulatus var. 
aerophilus (nos. 105 and 195). 
Trentepohlia umbrina (Körz.) Bornet, in WircLeE, Algol. Mit- 
theil. p. 426. [P1. IX and X, Fig. 264—289|. 
This species is of. very common occurrence on the bark of trees 
in several of the samples from the environs of Durban, but is 
entirely lacking in the samples from Saldanha Bay (mos. 9, 37, 85, 
108, 132, 133, 184, 153, 177, 179, 235, 248). 
The specimens drawn on the accompanying plates IX and X 
are all from sample 133. 
It will appear from the pictures of this widely distributed and 
variable species that in the South-African specimens the cells 
are usually more or less rounded, spherieal-ellipsoid or ovoid, at 
times even of a rather irregular shape. When young only, the cells 
are nearly cylindric and about 3—4 times as long as broad, with 
thinner walls, while the older ones, which are apt to be rounded off 
and to undergoing disintegration, have a thicker membrane exhibit- 
ing a distinet stratification. The membrane is always hyaline. 
These older thick-walled and isolated cells really act, and must be 
considered as the akinetes of the species. The ramification is very 
irregular, and this species rarely forms distinet filaments. The 
cells mostly lie in irregular rows in large heaps. frequently 
in several layers. The size of the cells is very varying, from 
quite small up to 35 u in diameter. The average size is 15—25 u. 
The thickness of the membrane is also very varying, 3—4 u, al 
times up to 7 u. The gametangies do not differ very much from 
the vegetative cells either in form or size. They may be terminal or 
intercalary. The diameter of the gametes is about 4 u, and they 
escape through a hole in the wall of the mother cell. 
The specimens from South Africa agree on the whole very well 
with the Scandinavian ones and with the material of this species 
in WITTROCK et NORDSTEDT, Algae Exsiccatae nos. 42, 915, and 14283. 
