Ventral and Ventro-Lateral : These are arbitrary terms used to define mesentery arrangement of the 8 primary mesenteries. The reason that these terms are arbitrary is because of the radial symmetry of the anemone, which makes the directive axis the only definable axis. The dorsal and ventral refer to the two directive couples and dorso-lateral and ventro-lateral for the lateral ones. The ventral directive couple is the one towards which the retractors on the four lateral mesenteries face (Carlgren, 1949; p. 9).