Schaubcylindrichnus heberti (Saporta, 1872)

Diagnosis Smooth walled, unomamented, thicklylined cylindrical burrows of somewhat variable orientation.

Straight to slightly curved, branched or unbranched, smooth-walled, cylindrical burrows; wall linings a significant part of the total diameter, the actual thicness varying with the size of the burrow. Exept among the collapsed specimens, the diameter of P. herberti segments tends to remain more or less constant, collapse are common, however, as are crossovers. Wall linings typically consist of agglutinated sediment, coarser and better sorted than that of adjacent rock; mica flakes, where present, are oriented concentrically with burrow walls. Preserved primarily as hypichnial ridges, less commonly as endichnia or epichnial grooves.