Diagram of an Annulosa
A diagram of an annulosa showing its external skeleton made up of segments or rings arranged along a longitudinal line, and consisting mostly of hardened skin. Labels: 1, vascular system,; 2, digestive organs; 3, ganglia.
Cutter, Calvin First Book on Analytic Anatomy, Physiology and Hygiene, Human and Comparative (Philadelphia: J. B. Lippincott & Co., 1875) 32