Translation 2816

53
1. Cells are ovoid to pyriform, 24-40f-{ in length with
(240) .
only six pre-equatorial plates, and no median apical plates; with
several spines`on the antapicàl plates .... . P. Cunnin:-tonii 1.
2. Cells are distinctly elongated, thinner, 30--40/q in
length with 7 pre-equatorial plates,.2 median apical plates, and
1 dorsal apical plate . . . . . . . . . . .. . . P. quadridens 2.
A. The dorsal apical.plate touches the apex and becomes plate 3'-
(244) .
1. Cells are ovoid, measuring 30 x 28Jq. Plates are smooth or
lightly punctate. The panelling pattern of the epivalve is
symmetrical , ^ . . . . . . . . . . . . . P.Penardii 1.
2. Cells are ellipsoidal or rhomboid, measuring 26-30 x 26-33;
the panelling pattern is asymmetrical .. P. berolinense 2,
B. The dorsal apical plate is remote fromthe apex:
3. Cells are ovoid or pyriform, often almost spherical, measuring
41--54 x 35-41^{ . Plates are frequently concave, faintly
areolated. vorsal apical plate is sexangular or pentangular.
P.Borgei3.
4. Cells are pentangular, 30-40A in length. Plates are plane
or slightly convex (rarely, one plate or another is concave).
Dorsal apical plate is pentangular. . . . P. penardifor.me 4.
5. Cells are ovoid, measuring 35 x 30R Plates are convex. Dorsal
apical plate is quadrangular. .... .. P. Kulczinskii 5.
While the panelling pattern is symmetrical in the species
P. Pene.rdii., tienardiî orme, Kulczinskii and BorLe:i 3 it is asymmetrial
in P. berolinense.