Translation 2816

55
3. Antapical horn points inwards, is relatively short, and
occasionally is almost parallel to the apical horn. (Cells
are often up to 50.4 in width). ' Brachyceroides type 4.
B. Short, wide, tricornute forms, over 45)q in width and 115-170/q
in length. The two posterior horns divaricate slightly.
Carinthiacum type 5.
C. Short or long forms, over 45 ,4 in width; tetracerous under__
conditions of optimal development; the left postequatorial
horn may be either short andtruncated or developed as a distinct
horn. Apical portion is conical, but less tall (than in A), and
usually much flatter, often even capshaped.
1. Postequatorial horns do not divaricate, or divaricate only
slightly. In general, forms are still somewhat thin.
(a)Antapical horn is directed in the sanie direction as the
apical horn, and right postequatorial horn is parallel to
the antapical horn, occasionally slightly divaricating.
Cell body usually is without dorsal convexity (along the
longitudinal axis). Ridges produced by thickening in the
cell membrane are fragile and reticular. Gracile type 6.
(263)
(b) Antapical horn and postequatorial horn point more outwards.
Entire cell bodyis dorsally convex (along the
longitudinal axis). Ridges produced by thickening in the
cell membrane are solid and usually irregular.
2obustum type 7.