What’s unusual about this limerick?

There was a young lady of Riga,
Who went for a ride on a tiger,
They came back from their ride
With the lady inside
And a smile on the face of the tiger.

It remains a limerick when translated into Latin:

Puella Rigensis ridebat,
Quam tigris in tergo vehebat,
Externa profecta
Interna revecta,
Risusque cum tigre manebat.

Ronald Knox found that the same is true of this one:

There was a young man of Devizes,
Whose ears were of different sizes;
The one that was small
Was no use at all,
But the other won several prizes.

Visas erat; huic geminarum
Dispar modus auricularum:
Minor haec nihili;
Palma triplici
Iam fecerat altera clarum.