David Pellegrino has assembled a useful collection of mnemonics for learning Latin
. In a speech
to the Association for the Reform of Latin Teaching, Dorothy Sayers (1893-1957) mentions one that isn't yet in Pellegrino's collection:
Abstract nouns in -io call
Feminina one and all;
Masculine will only be
Things that you can touch or see,
As curculio, vespertilio,
Pugio, scipio, and papilio,
With the nouns that number show
Such as ternio, senio.
And neither Pellegrino's collection nor a Google search shows this mnemonic for feminine fourth declension nouns that I vaguely remember from my schooldays:
A woman of a Latin tribus sat on the porticus of her domus with an acus in her manus stringing ficus on the Idus.
A woman of a Latin tribe sat on the porch of her house with a needle in her hand stringing figs on the Ides.