Diagnosis. Depressions subrectangular in outline during uniserial stage of development. Adjacent depressions communicate through a very shallow, short but wide furrow located at centre of contact zone.

Description. Elongate in overall shape. In the very short initial stage (composed of a maximum of five depressions), depressions are subrounded and⁄or oval in outline and show a spiral arrangement (Text-fig. 2A; Pl. 1, figs 1–2). The latter stage (composed of 7–16 depressions, with a mean of 11) is uniserial, forms either a straight or a curved path, with depressions subrectangular in outline that progressively increase in size towards the end of the trace (Text-fig. 2A; Pl. 1, figs 1–3). The length of the uniserial stage ranges between 9 and 30mm, averaging 18mm. All depressions are wider than long, having a length⁄width ratio of 1 : 1.6. Width values vary from 0.1–0.2 mm for the smallest depressions to 0.1–0.4 mm for the largest. Depressionlength varies from 0.1–0.4 mm in the smallest to 0.1–0.6mm in the largest examples. Depressions show no internal ornamentation and only communicate with one another through a very shallow, short and relatively wide furrow located in the centre of the contact zone and perpendicular to it (Pl. 1, figs 4–5). The width of this furrow is always less than 0.1mm, ranging between 44 and 90µm, with an average of 60µm. The edges of the depressions are marked by a very shallow, outer furrow (Text-fig. 2A; Pl. 1, figs 5–6) having a maximum width of 0.1 mm, although normally narrower and ranging between 27 and 69µm with an average of 46µm.