Colonial growth patterns and internal structures of Halysites from the Niagara Limestone 插畫檔

This illustration provides several views of a unique tabulate coral known as the chain coral, sourced from the Niagara Limestone of Canada. The specimens demonstrate the characteristic growth habit where individual coral tubes are joined at their edges to form winding, chain-like rows. One figure shows a life-sized cluster of a small variety, while another depicts a larger fragment with more robust tubes. A third view illustrates the appearance of these "chains" on the surface of a limestone block, revealing the characteristic loops and intersections that define the colony's architecture. Additionally, a highly magnified vertical cross-section of two tubes reveals the internal tabulæ, or horizontal partitions, which the polyps constructed as they grew upward. These corals were significant reef-builders in the shallow, warm seas of the Upper Silurian period.