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432
SYNDETOCYSTIS.
GENUS 100. SYNDETOCYSTIS RALFS. Manuscr.,
p.
1864.
Valves subcircular, with dentate
margins ; having in the centre a cylin-
drical process, curved into a hook,
which unites the valves to that of the
next frustule, and thus produces a
filament.
Syndocystis Barbadensis. having
We reproduce (fig. 155), after Walker
and Chase, Syridetocystis Barbadensis Ralfs,
a very curious form, found in the Cam-
bridge Estate Deposit, Barbadoes.
In the Manuscript for the Fifth
Edition of Pritchard, which forms part of
my library, Ralfs thus expresses
"
Syndetocystis N. G. Ralfs.
himself :
Frustules
as in Biddulphia, but connected in a
chain-like manner by strong spines from
the centre of their valves. The frustules
in the front view resemble those of the
other genera of this family, except in
from the centre of each valve a
stout central spine, which is suddenly bent near the end and curved in a link-
like manner round a similar spine from the adjacent frustule. In the fossil
state at least these spines slide upon each other, altering the distance between
the frustules, as is well shown in fig. 155, taken from a very perfect specimen
belonging to our friend Mr. Norman, of Hull.
"
S. Barbadensis Ralfn., also from Cambridge Deposit, Barbadoes. Mr.
Johnston.
" Valves broadly elliptical or suborbicular, with a process near each apex
and one or more subulate spines, which are best seen in the front view. Sur-
rounding the stout central spine is a large smooth portion, bordered by a
circlet of pearly granules, from which radiate rows of granules."