68 Transactions of the Royal Society of Soiith A frica. 
This differs somewhat from the Antarctic form originally described, 
especially in the highly flexuous character of the filaments, which are often 
very densely aggregated on the substratum, and in the fact that the apical 
cells of the trichomes are usually more rounded than in the type, being 
bluntly pointed rather than conical. The material, however, agrees in all 
Fig. 28. — Calothi'ix gracilis, F. E. Fritsch, forma flexuosa, n. f. A, group of 
filaments, the left-hand one with a young spore. B, base of a filament with 
a conical heterocyst and a developing spore. C and D, bases of other 
filaments. All figures x 1000. 
other essential respects with that from the Antarctic, and it is probable that 
it belongs to the same species. The heterocysts exhibit the same diversity 
of form as was commented upon in the description of the species. Ripe 
spores were not observed, but the young stages seem similar to those of the 
type (Fig. 28, A and B). 
