Annulosa included all segmented groups, thus arthropods also. In vol 1(2) ANA-ATW. Evidently there were three editions of this 1816 work, with possible minor changes between them. The Google books version in the linked pdf lacks the introductory but the meta data indicates it is the 1824 edition. The link above (Nat Library of Scotland) is also to the 1824 edition. Evenhuis (1997) "Literatura Taxonomica Dipterorum" dates Leach's Annulosa as first published June 1816
World Polychaeta Database (WPolyDb)
Available in Wilson Copepod Library (non-digital)