Planolites ballandus Webby, 1970

Diagnosis. - Simple, straight to sinuous horizontal, inclined and vcrtical burrows, mainly about 1 mm wide.

Description. - Discontinuous, curved to slightly sinuous ridge- and groovelike trails with scattered round to oval dome-like structures representing the tops of vertical to inclined burrows. Some horizontal trails seem to issue from inclined to vertical burrows (Fig. 14A). Occassionally horizontal trails cross one another. Trails are internal burrows, and are mainly 1 mm wide, though greater and lesser dimensions have been recorded, ranging from 0.3 to 2 mm; vertical and inclined burrows seem to have similar dimensions, except for a few which show larger dimensions than the associated horizontal trails (Fig. 14A). One in particular exhibits marked tapering as it emerges to become a horizontal trail, A section through a vertical burrow is shown in Fig. 14B. The burrow is somewhat irregular in form with a sudden constriction at one point; it is infilled with coarser sand than the surrounding laminated sediment.