Earlier I sent a note saying that I was not able to locate a copies of
the Bosch paintings mentioned here:
    According to Eliot (Poems, 1910-1930, p. 155), these details were
    inspired by a painting from the school of Hieronymus Bosch (a
    fifteenth-century Dutch artist), one called "Hell" or "The Sinful
    World" and forming a diptych with Bosch's "Deluge." In a part of the
    painting one can see a bat-like creature with dull human features
    crawling headfirst down a rock wall.

I've tried another search and I believe that I have found these paintings.
My new method was to search out the paintings in Dutch.  
    "Jheronimus Bosch" zondvloed hel rotterdam

I found the paintings at
The parent page is at

Unfortunately the images are very muddy.

    Rick Parker