From editor or global species database
Publication date The basionym Hydra verticillata is used in a volume of plates (Plate XLVII, figs 1, 2) dated 1822. There is no accompanying text in this volume. The same basionym is used on text-page 203 in a work dated 1828 that refers back to the 1822 plate. If the date of the volume of plates is correct, then, according to my reading of the Code (Article 12.2.7) the illustrations constitute a valid indication of the species name. Hence 1822 should be the date of publication (Dennis Gordon, pers. com.)
See also notes in Bedot (1905) [details]