FIGURE 4. Paraleucilla incomposita (UFBA 4532-POR, except for B, C, and D—UFBA 4533-POR). A—Preserved specimen and oscular fringe (in detail); B—Cross section showing the layer with subcortical lacunae (*) and free of choanocyte chambers (black line). Embryos (arrow) can be observed; C—Longitudinal section with a general view of the skeletal organisation from the cortical (cx) to the atrial (at) regions; D—Detail of the outer region (OR) and inner region below that; E—Cross section showing a choanosomal canal (cc) with apical actines of tetractines close to the atrium (at); F—Cross section of the atrium (at) with apical actines of tetractines protruding into it.