ABSTRACT
The fenestrate bryozoan Fenestella (s.l.) sculptilis Ulrich, 1886 from the Middle Devonian of the USA developed enigmatic channel-like structures on the obverse colony surface. These structures resemble the auxiliary tubes described in the literature as characteristic of the type D brood chambers, known only from the coeval Polypora (s.l.) shumardi Prout, 1858. Study of silicified specimens of F. sculptilis via optical microscopy and SEM shows type A brood chambers and other morphological differences with the type D brood chambers of Polypora (s.l.) shumardi. A detailed description of the channels present in Fenestella (s.l.) sculptilis is provided. Despite the scarcity of available data, a tentative discussion is undertaken regarding the nature of this singular feature as structures associated with breeding or, alternatively, the result of symbiotic interaction.
