Diagnosis: Elongate, smooth borings of circular section with a calcareous lining; lateral, calcareous, meniscate structures parallel one side of the borehole only.

Description: Aperture and neck not preserved in any specimen; base of boring not seen. Borings smooth, elongate (‘torpedo-like’) in longitudinal profile (best seen on TF 147(4), preserved as an oblique section; Fig. 2B) and circular in section throughout. Longest specimens 30+ mm long but incomplete. All boreholes lined by a calcareous (calcite?) layer. Finely laminated, calcareous meniscate structures preserved adjacent tohe borehole are as wide and long as, and concave towards, the boring, The longest “train” of menisci is more than 20 mm inlength. All borings preserve the shell of the producer, a bivalve mollusc.