"Opus 181" by Arthur Davison Ficke was offered by Poets.org's Poem-A-Day on December 7, 2013. A link to the poem may be found here:
Arthur Davison Ficke (1883 - 1945) was an American poet and lawyer. He co-founded the Spectric School of Modernist Poetry that mocked the popular modernist poets of his time.
The poem consists of two stanzas, the first of thirteen lines, and the last of only one line. Accordingly, there is at least a nod to the sonnet form.
There is something of the werewolf, or werecat, in this poem, with its references to the moon, to fingers sprouting claws, and to the pupils of feral eyes changing shape. The chilling final line implies cannibalism, fratricide, and murder.