10 
Transactions of the Koyal Society of South Africa. 
Yar. apiculatwn, F. E. Fritsch, nov. var. (Fig. 2). 
Coenobiis e cellulis 4 vel 8 (disp. : 7-1) constant ibus ; cellulis margi- 
nalibus processibus 2 plus minus divergentibus, in apice pauUo dilatatis et 
membrana iucrassata; inter cellulas marginales membrana exterior saepe 
est incrassata et plus minus prominens forma apiculi, Lat. colon. 4-cell., 
22 fA,; lat. colon. 8-cell., 24-40 /x; lat. cell., 9-16 /x. 
Samples 71 (rare) and 345 (rather rare). 
It is possible that this should be regarded as a separate species, but 
the relatively little material available was not sufficient to settle this point. 
In particular the four-celled stage (Fig. 2, D), bears, except for tlie charac- 
teristic apiculus at the end of each marginal process, a considerable 
Fig. 2. — Pediastrum tetras (Ehrenb.), Ealfs, var. o.piculatum, F. E. Fritsch, 
nov. var. A and B, eight-celled, D, four-celled colonies ; C, abnormal colony. 
X 1000. 
resemblance to some of the simpler colonies of P. tetras {cf. especially 
Ealfs, loc. cit., Tab. XXXI, fig. 1, D). It is to be noticed that the depth 
of the incision between the marginal processes, as well as the shape of the 
latter, are rather variable. On the whole the incision tends to be wider 
and blunter than in the type ; this applies also to the single, centrally placed, 
cell of the eight-celled colonies. 
A second characteristic of the variety, apart from the apiculate processes, 
lies in the presence of a more or less marked thickening of the external 
membrane at a point coinciding with the septum between two marginal 
cells (Fig. 2, A, B, C) ; in some cases this thickening is so marked as to 
amount to a definite projection. 
