The Snail and the Mouse by Laura E. Richards

The snail and the mouse
Went round the house,
Running a race together;
The riders were elves,
And proud of themselves,
For neither weighed more than a feather.

The snail went crawly, creepy, crawl,
The mouse went hoppety hop, sir;
But they came to a fence
That was so immense
(Six inches!), they had to stop, sir!