26 HENRIK PRINTZ [1920 
is no doubt very rare in this alga. Though I have observed the 
species in several samples, in many of which it has occurred in 
abundance, I have found aplanospores in a single only. Neither 
have they ever been found by anyone else before. 
With regard to the systematical position of this alga, it can, as 
previously mentioned, on account of its reproduction, hardly be 
referred to the Trentepohliaceae, which, by the way, as to reproduc- 
tive organs, form å homogeneous and well defined family. In its apla- 
nospores, on the contrary, it exhibits resemblance to the Wittrockiel- 
laceae. In the structure of the vegetative thallus it differs from 
both the families mentioned. It is as yet uncertain whether this 
species also has motile spores, though it must be considered impro- 
bable. Akinetes, which occur both in the Trentepohliaceae amd the 
Wittrockiellaceae, I have not been able to point out in Physolinum, 
as setae are also entirely lacking. In many ways it seems to be inter- 
mediate between the families mentioned, most likely representing 
an entirely new family, but this I will leave unsettled until the 
development and structure of this peculiar alga is better known. 
The species is rather common in many of the samples from the 
environs of Durban, but I have not found it in any sample from 
Saldanha Bay (nos. 30, 57, 105, 120, 122. 134, 154, 169, 214, 238, 260, 
261, and 29). 
Trentepohlia aurea (L.)Martius forma. [P1. VII and VIII, Fig. 
244—2631. 
To begin with I was much in doubt whether it would be right to 
refer the species of Trentepohlia, drawn in the plates VII and VIII, 
fig. 244—263 to Trentepohlia aurea or to Tr. abietina. The real dif- 
ference between these two species, by the way, seems to me, to be 
so slight that it may be dubious whether it is correct to maintain 
Tr. abietina as a species different from Tr. aurea. 'The various 
authors agree that they are nearly allied. but the views as to where 
the lines between them should be drawn, on the other hand, seem 
to be very vague and varying. 
An attempt at drawing a line between the two species, on the 
basis of the existing literature, will show that much uncertainty is 
reigning. Let me state some instances: De Wirpeman (Les Tren- 
tepohlia des Ind-Neerland. 1890), for instance, attaches much 
importance to the fact that one (Tr. aurea) is said to have eylindrie 
cells, while those of Tr. abietina are more inflated and elliptic. The 
last mentioned species is said, however, to constitute å iransition 
beiween these two groups, as it may sometimes be found with 
rectangular (cylindrie) cells. Harrot (Notes sur le Genre Trentepoh- 
lia, 1889—90), on the other hand, refers both species to the one 
group of the species of Trentepohlia, being distinguished by «cellulae 
cylindricae». This character is, accordingly, very doubtful, and 
