Unfortunately, I cannot help you as I do not know what you want in the next chapter. If you can provide me with the plot summary and things, I can help you and give you a few tips. I can proofread if you like, though.
"Free Verse" is the correct answer. Free verse doesn't follow any specific rules or guidelines, unlike other forms of poetry.
In The Metamorphosis of the Dnieper, the Volga, and the Dvina (which are all rivers in Russia), the purpose of mythology that the story fulfills is explanation of natural phenomena. The creation of these rivers is what makes the plot of the story.
