Circulodinium attadalicum, (Cookson and Eisenack, 1962), Helby, 1987

Originally Cyclonephelium?, subsequently Aptea, thirdly Canningia, fourthly (and now) Circulodinium.

Holotype: Cookson and Eisenack, 1962b, pl.5, fig.13
Locus typicus: Perth Basin, W. Australia
Stratum typicum: Aptian-Albian

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Cyclonephelium attadalicum: [Cookson and Eisenack, 1962, p. 495]:

Description:
Shell small, slightly biconvex, more or less polygonal in outline with a broadly indented base, one of the basal projections being more prominent than the other.
Surface ornamented with small, stiff, frequently capitate appandages which tend to be grouped in intervals around the shell, especially in the antapical region. The central portions of both surfaces are relatively free from appandages except in the equatorial region of one surface, which, in well-preserved examples, is crossed by two rows of appandages that appear to delimit a girdle like zone. Usually, on the opposite surface a slight deepening runs from the limits of the girdle zone to the antapex.
No complete specimens have been observed, but it is clear that the shells opened by the detachment of the apex along a nearly straight or zig-zag line.

Dimensions:
Holotype: overall width 82 µm, width of shell 72 µm, range: overall width 70-80 µm, width of shell 60-77 µm.