Read these lines from Canto XXII:



A. Demon armies marching with Dante

B. Demons torturing sinners

C. Frogs covering the ground

D. Rivers of Hell converging


So here on all sides these sinners squatted,

But the instant Barbariccia stepped forward,

They dived back underneath the boiling pitch.


I saw, and still my heart shudders with it,

One lag behind — just as sometimes one frog

Will stay back while another leaps below —


And Graffiacane, the closest to him,

Hooked him up by his pitch-knotted hair

And hauled him out — he looked just like an otter!

What is Dante describing here?