Gonyaulacysta sp. A Davey 1979

Reference: Davey, 1969, pl. 1, figs. 9-10
Occurrence: Fetchum Mill, England
Age: Cenomanian, Upper Cretaceous

Original description: Davey, 1969, p. 124
Only one well preserved specimen of this species has so far been observed. It possesses a subspherical shell, bearing a moderately well developed horn with a trifid termination. The shell wall (c. 2,u thick) is irregularly studded with granules of varying shapes and sizes. The sutural crests are quite well defined, but low, and indicate a reflected tabulation of 3", Ia, 6", 6c, 6""" (--7"""?), 1p., 1"""".
The crests, demarcating the three apical plate,s, extend along the apical horn and
give rise to three small spines at its distal termination. Plates 2", 3" and 4" are
relatively large, plates 1" and 5" rather elongate and plate 6" is reduced due to the
anterior intercalary plate. In the postcingular series, plates 1""" and 2""" are
reduced and plate 7""" does not have a clearly marked plate boundary. Plate 2"""
possesses a curved line of ornamentation which is characteristic of Cribroperidinium Neale & Sarjeant. There is a single posterior intercalary plate and a large antapical plate.
The cingulum is strongly laevo-rotatory and varies considerably in width (2-5 Á),
being constricted at the cingular plate boundaries and expanding on either side.
The sulcus is broad and possesses a central depressed area of elongate shape. A
archaeopyle is present.