Straight to slightly curved cylindrical to subcylindrical burrows, parallel or slightly inclined to bedding. True branching not observed, only intersections. Burrow margin with discrete lining and without ornamentation. Burrow fill composed of sediment identical to that of the host rock. Burrow diameter varying within the same sample, being 4.55 mm in average. Preservation in positive hyporelief.
Diagnosis. Smooth-walled, unornamented, straight to sinuous cylindrical burrows, thinly but distinctly lined (Pemberton and Frey, 1982; modified by Frey and Howard, 1985).
Straight to sinuous, horizontal, commonly unbranched, thinly lined to unlined, smooth-walled cylindrical, endichnal burrow. Some specimens display primary or secondary successiv branching. Burrow diametr is 5.1-11.3 mm. Maximum lenght observed is 9.1mm. Burrow-fill is similar to the host rock and massiv. No evidence of burrow collapse has been detected. Preserved as both positive hyporelief and epirelief.
Cylindrical burrows branching dichotomously, varying in shape, unornamented. In cross section they are oval, 2-5 mm in diameter. Convex hyporeliefs.
Stright to slightly curved, more or less smooth-walled burrows, with thin but conspicuous linings. True branching is comparatively rare and irregular, crossovers, interpenetrations and collapse features are common. Dimensions vary within given specimens, although some segments may be straight and consistently cylindrical for appreciable lengths. Rarer spacimens may be highly curved or meandrous. Striations may be present locally but rare faint and inconsistently developed. Preserved as endichna or, more commonly as hypichnal ridges or epichnal grooves.