Article: Multilamellar growth in two Jurassic cyclostomatous Bryozoa

The bryozoans Repiomultisparsa incrustans d'Orbigny and Mesenteripora undulata (Michelin) constructed multilamellar zoaria composed of a succession of overgrowing zooecial layers. The lanonomic status of the two species is reviewed briefly, and a mode of formation of the multilamellar zoarium common to both species is described. This involves overgrowth of old zooecia by young zooecia budded at C-shaped growth margins, the two ends of which remain stationary and function as points about which growth pivots. Complex patterns of growth result from the interactions between adjacent growth margins. The implications of this mode of growth to the colony during life are discussed.