Genus Filograna Oken, 1815
Filograna filosa (Dujardin, 1837)
Pl. 1, fig. 4.
Description – Tube small, 0.25-0.50 mm in diameter; diameter increasing very slowly. Many tubes are found attached more or less parallel to each other, thus forming bundle-shaped aggregates. The bundles may ramify and unite to form a mesh-like plaiting. Commonly, the tubes lack any ornament. The tube wall is thin, so that not only the outline, but occasionally also the lumen may be deformed polygonally. In contrast to Glomerula, Filograna never shows a trilobate narrowing of the lumen.
Remarks – Filograna filosa may be confused with worn cyclostome bryozoans and with constructions made by the polychaete Dodecaceria (family Cirratulidae).
Distribution – Meerssen Member, principally in the upper part of section IVf-6, mostly in the Geulhem/Berg en Terblijt area (the Netherlands). The total known range of this species is Late Jurassic to latest Maastrichtian; common, extant species of Filograna are widespread and similar to F. filosa.