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Impagidinium subtilis
Plate 23, Figures 9, 10, 14, 16, 20
Holotype: Plate 23, Figure 16.
Type Locality: Well 14/19-21 at 10404.50ft (conventional core chip), late Hauterivian. Holotype: Well 14/19-21, slide 10404.50ft/2. E.F. N63.4.
Derivation of Name: From the Latin subtilis, fine, delicate - in reference to the thin-walled nature of this species.
Diagnosis: Asmall to intermediate, thin-walled, proximate species. Subcircular to pentagonal in outline, smooth with patches of low, vermiculate to irregularly reticulate mesotabular ornament. Tabulation apparently typical of the genus is marked by low crests of even height which are distally entire or bear a row of numerous, very low denticles. The archeopyle is precingular, formed by loss of plate 3".
Dimensions: Holotype: Length - 53 μm. Width - 53 μm.
Overall: 63 (54) 48 μm × 53 (53) 51 μm.
Specimens Measured: 5.
Remarks: This species is relatively small and is characterised by being atypically thin-walled for this genus and by its unusual mesotabular ornament. It has a very restricted stratigraphic range in the present study, being observed only at 10404.50ft in well 14/19-21 and at 8870.70ft in well 14/19-19; both samples are within the late Hauterivian, close to the LKP16.1/LKP16.2 sub-zonal boundary. It was also recorded in Bed C3 at Speeton (late Hauterivian, marginatus ammonite Zone).
Holotype: Plate 23, Figure 16.
Type Locality: Well 14/19-21 at 10404.50ft (conventional core chip), late Hauterivian. Holotype: Well 14/19-21, slide 10404.50ft/2. E.F. N63.4.
Derivation of Name: From the Latin subtilis, fine, delicate - in reference to the thin-walled nature of this species.
Diagnosis: Asmall to intermediate, thin-walled, proximate species. Subcircular to pentagonal in outline, smooth with patches of low, vermiculate to irregularly reticulate mesotabular ornament. Tabulation apparently typical of the genus is marked by low crests of even height which are distally entire or bear a row of numerous, very low denticles. The archeopyle is precingular, formed by loss of plate 3".
Dimensions: Holotype: Length - 53 μm. Width - 53 μm.
Overall: 63 (54) 48 μm × 53 (53) 51 μm.
Specimens Measured: 5.
Remarks: This species is relatively small and is characterised by being atypically thin-walled for this genus and by its unusual mesotabular ornament. It has a very restricted stratigraphic range in the present study, being observed only at 10404.50ft in well 14/19-21 and at 8870.70ft in well 14/19-19; both samples are within the late Hauterivian, close to the LKP16.1/LKP16.2 sub-zonal boundary. It was also recorded in Bed C3 at Speeton (late Hauterivian, marginatus ammonite Zone).