"Snail, snail, first your head" seems to be a variant of the following singing game "Snail":

The Song:
Snail, snail, come out and be fed
First your feelers, then your head
Then your Mama and your Papa
Will feed you mutton fries, mutton!

The Game: Everyone starts in a circle, holding hands. As you sing the song, turn it into a spiral (like a snail's shell) as you skip around. When you're all coiled up, reverse direction and unwind the snail!

SOURCE: HERE.

~Masato