Their eyeballs roll, their blond legs burn like brush.
So yeah, these dogs don't look too friendly with their rolling eyeballs and burning legs. They sound pretty hellish in fact. (Disclaimer: the following photo from The Exorcist provides a good idea of what these "rolling eyeballs" might look like, but is not for the faint of heart.)
And just like we saw in the previous lines about the librarian, Strand is keeping this image together without any periods between them. So we see these hellish dogs in one relatively fluid moment with only a comma to make us pause for a second.
But why are things suddenly looking so hellish? We thought the speaker was as happy as can be.
Like we saw before, joyous moments can't last forever, and sometimes we might go from feeling really happy to really sad or even frightened. Our emotions can feel like a rollercoaster sometimes.
So the same thing seems to be happening here. While the speaker was eating poetry, he was super-happy. And now that he's eaten all the poems, there's nothing left, so now those hellish dogs are on their way up ready to wreak havoc on the speaker's mind.
We don't get any specifics as to how these dogs will influence the speaker, but we do know that there's some darkness there nonetheless. So the ambiguity here allows us to fill in the blanks based on our own associations with hellish dogs.
Also we see some alliteration here with "blond" "burn" and "brush." So our attention is really drawn to the appearance of those burning legs, which helps to accent Strand's surrealistic imagery.
"Brush" here is not the thing you comb your hair with, though. It's the stuff you see out in the woods that burns pretty easily, like weeds and small sticks.
Those dogs seem to be literally on fire here, which adds to their rather hellish appearance and powerful influence.
The poor librarian begins to stamp her feet and weep.
We can't be too sure if the librarian is weeping because she sees the same burning dogs that the speaker does. But we know she was sad to begin with, so now it looks like she's feeling even worse.
More importantly, this line really accents the shift in mood that's occurred. Things have escalated in a way that's gone from joyous to surrealistically dark and chaotic even.
We get the sense that neither joy nor darkness can exist by themselves in this poem. They're mingling with one another and transitioning from one to the other right before our eyes (trippy).
Meanwhile, the librarian just doesn't get any of it, so she stamps her feet and weeps. The speaker though seems to have a better understanding of what's going on even if we don't. In a way, we're also like the librarian seeing all this weird stuff and trying to figure it out.
Notice too the assonance we hear in "feet" and "weep," accenting that long E sound. So the stamping and weeping kind of blend into one another like the other characteristics used to describe the librarian in the second stanza. (Check out "Sound Check" for more good stuff on the sound of this poem.)