Thanks for those links.
Meanwhile, back around the campfire, we found most listed on this Google group (including the later publication):
Note, there is "Die Ameise oder Bemerkungen Charakterzüge" (& from 1812 to 1815) issue 30 from 1818.
This also carried the title of "Das Echo"
There is a transition, explained in volume 28 (though the volume only has "Das Echo" the dual titles are claimed):
Seems the binding was such as to use Das Echo as this one is Dritten Bandes viertes Heft yet is listed on Google as "volume 31"
Guess one just have to stay on one's toes & take care. - R