Nr. 1] SUBAKRIAL ALGAE FROM SOUTH AFRICA 27 



with our knowledge of other species of the genus in this regard, 

 wnere tlie shape of the cells may be ve ry varying — not only in the 

 proportions of length and breadth, but also as to the shape of the 

 cells on tlie wliole — tliis cKaracter does not seem to be a suitable 

 basis for the distinction of species. Thus, boith cylindric ajnd 

 inflated cells are to be found together in the same species, not in 

 one and the sanie sample only, but even in Ihe very same filament. 

 Other authors attach great importance to the breadth of the cells, 

 Tr. abietina being recorded to have narrower celLs than Tr. aurea, 

 but the range of variation of both species with regard to this is very 

 large, and as the limits of both species not only are drawn very 

 differently by the various authors, but even over-lap (Tr. aurea 

 8 — 30 jii and Tr. abietina 4 — 10 ju), is does not seem possible, also 

 with our experiences from otlier species in the genus — to base a 

 distinction between the two species on this character either. 



I have really been looking in vain for a good systematic charac- 

 ter on which might be Imsed a distinction between these two species. 

 Hariot, indeed, says: 1. c. p. 52 on Tr. abietina: «Tr. aiireae formis 

 gracilioribus adeo proxima iit non certe nliquando distinguaiur». 

 Neither the shape, size nor arrangement of the sporangies seem to 

 give safe hold with regard to a distinction between the species men- 

 tioned, as both of them, as known, are subjecled to considerable 

 variations, and the limitations also in this respect must be made 

 very wide. 



The accompanying piates VII and VIII will give an idea of the 

 appearance of the specimens fomid by me. The cells are cylindric, 

 or slightly inflated, 6—10, usually 7—9 jli broad, 1—2 times, usually 

 1)4 times as long as broad. In some samples, however, are to be 

 found broader filaments, to 17 « broad (sample no. 294). They form 

 long, straight, or slightly curved filaments, more or less branched 

 in various ways. The branches are sometimes spreading, at nearly 

 right angles; or more appressed. The cells of the branches do not 

 differ perceptibly either in thickness or in length from Ihose of the 

 main filament. The terminal cells are never acute al the top, but 

 generally ralher oblusely rounded. The membrane is comi:)aratively 

 thin and colourless, glabrous, or stmietimes finely crenulate. A real 

 reticulation is nol to be found on the membrane, however. The 

 gametangies are usually spherical, rarely slightly ellipsoid, or at 

 itimes ovoid, 15 — 25 jli in diameter. Their memlnane is thin and 

 glabrous, or crenulate. Specimens with crenulate membranes, 

 however, may at times have glabrous gametangies. The game- 

 tangies are terminal or lateral, borne direclly on the vegetative 

 cells, and are to be found bolh on the main filament and on the 

 branche,s, singly or in series. Al limes, two gametangies may arise 

 from one vegetative cell. (PI. VIII, fig. 250 and 252). The game- 

 tangies are opened by a hole in the membrane, through which the 



