Translation 2816

49
A. Cells are ovoid to conical; path of transverse groove runs
below the middle of the body, so that the epivalve is larger than
the hypovalve.
1. •Pedicles present, crests on the epivalve. P. bipes 1.
2. Pedicles are sharply reduced, crests present.
P. bipes var. occultatum
3. Pedicles are completely absent, as are the crests.
P. bipes var. tabulatum
B. Cells are spherical; transverse groove runs equatorially, so that
the epivalve and the hypovalve are of approximately equal size.
Pedicles are absent, epivalve crests present.
P. Plavfairii 2.
C. Cells are pentagular, bulky. Apex is bent over towards the left;
posterior part of body is bilobate, crests on the epivalve and
the hypovalve P limbatum 3.
D. Cells are rhomboid. Edges of the longitudinal groove are elevated,
with rounded ends prominent on the posterior part of the body,
which often have the appearance of spines. Chromatophores are
absent. Fresh and brackish water form. P. achromaticum 4.
Another species, which certainly shows the same panelling
pattern, but otherwise is of _a différent type (P. wisconsinense
EDD;Wiwas assigned to this group as an appendage and subsequently
transferred to the Allorr-ei group.