This poem from Clark Ashton Smith (CAS) is in terza rima, a poetic form most strongly associated with Dante Alighieri's Divine Comedy. The subject matter is directly linked to CAS' short story "Morthylla" and its evocative ending:
To his startlement a woman, or what appeared to be such, was sitting on a fallen shaft beside the mausoleum. He could not see her distinctly; the tomb's shadow still enveloped her from the shoulders downward. The face alone, glimmering wanly, was lifted to the rising moon. Its profile was such as he had seen on antique coins."Who are you?" he asked, with a curiosity that overpowered his courtesy."I am the lamia Morthylla," she replied.
"Lamia" is dripping with the same sort of sepulchral ambience:
Her lethal beauty like a philtre stirred
Through all my blood and filled my heart with light:
I wedded her with ardor undeterred
By the strange mottlings of her body white,
By the things that crept across us in her den
And the dead who lay beside us through the night.
The closing line of the poem really seals the deal: "It is a thousand years since I have died."
The thematic links among CAS' work in poetry, prose, and poems in prose are often quite strong, with his fictional setting Zothique often providing the connecting thread. This seems to be the case with "Lamia", as the poem provides something of a coda to "Morthylla". This is just part of the reason that reading his poetry can be so rewarding, as it amplifies the best elements of his better-known work in fiction.