Entobia solaris Mikuláš, 1992

Description: System of borings consisting usually of one chamber (of 5 chambers at the most) of spherical or hemispherical form of straight, or moderately curved, exceptionally branching exploratory threads. The chamber (or chambers) is immediately connected with the environment by a broad aperture whose diameter is generally about one half that of the chamber. In hemispherical chambers the apertures and chambers have diameters of the same size. From the aperture the exploratory threads run radially, following the surface of the substrate. There are usually 5 to 20 in number. In case they are straight, Pl. I, figs. 1, 4, the boring has a star-like shape. They are, however, regularly bent (from the chamber to the margin of the boring and all turn either to left or right) and the boring is then of a "weather-cock" shape. Exploratory threads and chambers of small or minute diameters represent the growth phase A. During the further growth the diameter of the chamber increases and the exploratory threads are "rebored" to a larger common width. The specimen in Pl. I, fig. 4 demonstrates that the "re-boring"to a larger diameter is not gradual but it occurs at a time, from the chamber towards the ends of threads. This growth of boring I regard as equivalent to growth phases B-D of Bromley and D'Alessandro (1984). The concluding phase E is probably represented by specimen on Pl. III, fig. 6: huge hemispherical chamber, which "consumed"the major part of the surrounding exploratory system.