ABSTRACT
The bryozoan genus Umbonula Hincks, 1880 is the type genus of the family Umbonulidae Canu, 1904. Harmer (1902) described the formation of the frontal shield in the type species, using the descriptor ‘umbonuloid’ for this mode of development. The term is now well known and describes frontal shields in a wide range of taxa that are collectively known as umbonulomorph. In these forms, the primary frontal membranous wall of the zooid is overarched by a complex fold that is outwardly interior-walled with a hypostegal coelom, while, on the underside, the surface is exterior wall with planar-spherulitic skeletal microstructure (Sandberg 1977).
