Acteocina canaliculata (Say, 1826) reaches only 5 mm (0.2 inch). The shell is thin, slightly pear-shaped, and the spire usually spans less than 1/5 of the shell length. The protoconch (larval shell, on top) is set at 90º to the adult shell. Barrel bubbles are cephalaspidean gastropods, and, as such, have a well-defined cephalic shield. Very similar to Acteocina candei (d’Orbigny, 1841), but this latter tends to have a taller spire, being more common in open-water locations.
