Leach (1816) created Cistena for a new species name of 'Pallassii' [note spellling], but he included Nereis cylindraria Pallas, Sabella tubiformis Pennant and Nereis conchilega Pennant as its synonyms. Sabella tubiformis is a tube only (p.372 in Pennant iv, with Pallas 'belgica' as a synonym, and Amphitrite auricoma (Pennant p.91) as the worm in the tube.
As Nereis cylindraria is an available name Pennant's Cistena pallassii could be considered an unnecessary replacement name for it, thus invalid for nomenclature. Cistena was suppressed by the ICZN opinion 1225, and Cistena pallassii was rejected as invalid by the ICZN, but apparently for reasons to maintain existing usages for Pectinaria, and not to do with them being superfluous new names.
International Commission on Zoological Nomenclature (ICZN). (1982). OPINION 1225: Pectinaria Lamarck, 1818, Nereis cylindraria belgica Pallas, 1766 and Lagis koreni Malmgren, 1866 (Polychaeta): conserved. <em>Bulletin of Zoological Nomenclature.</em> 39(3): 186-191.available online athttp://biodiversitylibrary.org/page/12228099 Available for editors [request]
Leach, W.E. (1816). Annulosa. In: Encyclopedia Britannica, supplement to the fourth, fifth and sixth editions 1:401-453, pls. 20-26. (vi-1816)