The
snake comes out as through "from the burning
bowels of the earth /On the day of Sicilian July, with Etna smoking."
Lawrence is imagining that the snake is descended from the mythological
serpent Typhon. Here is The myth of the volcano Mt. Aetna and Typhon:
Typhon
was born from Gaia (Mother Earth) and Tartarus. This was Gaia's youngest
offspring, but by far the deadliest and the largest monster ever conceived.
Its thighs were gigantic coiled serpents; its arms could spread across
the heavens, and its head (in the shape of an ass's head) touched the stars.
When it took flight, its wings blotted out the sun, and when it opened
its mouth, out came burning boulders. Typhon was so frightful even the
gods of Olympus refused to fight, fleeing instead to Egypt when Typhon
attacked their mountain home. Each god disguised itself into an animal:
Zeus transformed himself into a ram, Dionysus a goat, and so on. Aphrodite
and Eros both disguised themselves as fish and swam up the Nile to escape
the monster. Typhon was eventually defeated, due in large part to the brave
and level-headed Athene, who convinced Zeus to take up his thunderbolts
and make battle. Typhon actually captured Zeus and placed him in a cave,
but Hermes and Pan were able to free him. To make a long story short, Zeus
then took the battle to Typhon, chasing him to Sicily. There Zeus threw
Mount Aetna at the monster, finally subduing it. But under the earth, the
buried monster still spews up fire and boulders every so often.