Article: The Silurian brachiopod Eocoelia hemisphaerica (J. de C. Sowerby) and related species
The atrypacean Eocoelia occurs widely in the Upper Llandovery and is now known from the lower Wenlock. It shows evolutionary trends in the progressive suppression of ribs and in the modification and strengthening of the articulatory mechanism. These trends are used to define four successive species, Eocoelia hemisphaerica (J. de C. Sowerby) of C1-C2 age, E. intermedia (Hall) of C3-C4 age, E. curtisi sp. nov. of C5 age, and E, sulcata (Prouty) of C6-Wenlock age. The taxa Eocoelia hemisphaerica sefinensis (Williams) and Eocoelia quebecemis Amos and Boucot are relegated to the synonymy of Eocoelia hemisphaerica. Because of the abundance of Eocoelia at some localities, the term Eocoelia Community seems appropriate; this community probably occurred in a near-shore environment. Brachiopod lineages, such as the Eocoelia lineage, provide a reliable basis for fine-scale correlation.