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Bryozoa
Umbonula aff. littoralis Hastings, 1944
SUMMARY
Colonies are encrusting, multiserial and sheet-like. The ancestrula and early astogeny have not been described in Crag material of this species.
Autozooids are rounded rhomboidal in outline shape, slightly longer than wide, about 0.56-0.77 mm long by 0.35-0.48 mm wide. The frontal shield is convex and finely granular, bordered by multiple, radially elongated areolar pores, and lacks pseudopores. A low umbo is situated over the suboral avicularium. The large primary orifice is hemielliptical with a convex proximal edge, somewhat wider than long, about 0.26 mm long by 0.28 mm wide, and occupies almost half of the frontal area of the zooid. Oral spines are lacking. Ovicells are absent.
A suboral adventitious avicularium is present in most zooids, inclined almost perpendicular to the plane of the autozooid and with a large chamber that becomes visible in worn examples. In better preserved material from Belgium the proximally directed rostrum is rounded.