ill!Ill

Frustule almost rectangular, three times longer
AMPHORA. 129
than broad. Valve linear
with apices broad, unilaterally rounded. Raphe gently bi-arcuate, distant
from ventral side. Axial area indistinct on dorsal side. Central area absent
or orbicular. Striae of dorsal side 10 to 14 in 1 c.d.m., coarsely punctate, not
interrupted, with indistinct longitudinal line. Ventral side broad, with striae
radiant, coarsely punctate, sometimes crossed by a narrow hyaline band.
Length of frustule, 4 to 7 c.d.m. Breadth, 17
valve,
1 c.d.m.
Marine. Coasts of Belgium and England (Cleve).
Var. major A. Baltic Sea (CI).
to 2-1 c.d.m. Breadth of
A. marina H. Van Heurck (h.v.h. Atl., pi. i,
in Types Nos. 101 and 517), plate 1, fig. 14.
f. 16*;
Frustule oblong, very inflated at median part, infinitesimally attenuated as
far as the apices which are truncate. Valves with dorsal margin very convex,
and ventral margin slightly and almost regularly concave ; raphe well marked,
inflexed at median part ; striae rather strongly punctated on dorsal side ;
about 16 in 1 c.d.m., same number at ventral margin. Length, 4 to 5 c.d.m.
Marine. Shores of North Sea: England (W. Sm.), France (Grun. , Brdb.), Belgium: Scheldt.
(H. Van Hk. and ), probably on all shores of North Sea.
According to Prof. Cleve this form should be recorded as having been
first described by me, and the A. marina of Wm. Smith treated as only a form
of A. Proteus.
A. robusta Greg. (Diat. of Clyde, p. 44, pi. 5, f. 79; Ad. S.
Atl, pi. 27, f. 40-41*); plate 24, f. 670.
Frustule broadly oval with truncate or sub-truncate apices.
Valve arcuate,
with apices obtuse, raphe very inflexed, central nodule large, surrounded by a
blank space slightly stauroform. Ventral margin concave. Ventral part of
valve completely striated, striae with coarse puncta, 7 to 8 in 1 c.d.m. Sutural
zone completely smooth. Length, 8 to n c.d.m.
Marine, Scotland (Gregory) and Shores of North Sea; Belgium: Scheldt (H. Van Hk.)
A. Proteus Greg. (Diat. of Clyde, p. 46, pi. 5,
Atl., pi. 27, f. 2-3; 5-6*); plate 24, fig. 671.
f. 81; Ad. Sch.
Frustule elliptic, with truncate apices. Valve with dorsal margin arcuate,
ventral margin concave, apices obtuse. Raphe very inflexed ;
central nodule
K