Your fluted bones and acanthine hair are littered
In their old anarchy to the horizon-line. (20-21)
Yay—more bones. The speaker takes the mention of "skull-plates" from line 14 even farther this time and gives us an image of a vast bone-yard that stretches as far as the eye can see. Is it just us, or has the speaker picked a really depressing place to hang out? If you want to get all metaphorical with your interpretation, you could say that this represents the way she feels completely surrounded by death.
The sun rises under the pillar of your tongue. My hours are married to shadow. (27-28)
Even though the sun is rising, the speaker is more concerned with the dark. You could totally interpret this line to mean that though life is going on around her she is stuck in mourning-mode.