This 1877 marble sculpture is entitled "Cassandre se met sous la protection de Pallas" or "Cassandra places herself under the protection of Pallas".
The work depicts her naked but for a cloth over her thigh. She is standing next to a square pedestal that has a small statue above it- presumably representing Pallas.
Cassandra is a difficult figure because different legends have been attributed to her. but the major theme is that Cassandra gained the gift of foresight; but after she spurned Apollo's love, he placed a curse on her that would cause no one to believe her predictions. 
There are several Pallas's in mythology too and presumably this Pallas refers to Athena who was also known as Pallas Athena.

The artist is French sculptor Aime Millet (1819-1891). Millet was the son of miniaturist Frederick Millet (1796-1859) and uncle to Chicago architectural decorator Julian Louis Millet (1856-1923). He studied and made first in 1836 at the École des Beaux Arts with David d'Angers and Viollet-le-Duc, who was later to design the base of Millet's statue of Vercingetorix in Alesia.

In 1840 Millet began to produce his early works, in 1859 received the Légion d'honneur, and in February 1870 was appointed professor at the École des Arts décoratifs. He was a friend of sculptor Pierre Louis Rouillard and his students included Louis Majorelle, Berthe Morisot, and François Pompon.

Millet died in Paris on January 14, 1891, and is buried in Montmartre Cemetery."

Cassandra also known as Alexandra or Kassandra, was the daughter of King Priamand Queen Hecuba of Troy.

A common version of her story is that Apollo gave her the power of prophecy in order to seduce her, but when she refused, he spit into her mouth cursing her to never be believed. In an alternative version, she fell asleep in a temple, and snakes licked (or whispered in) her ears so that she was able to hear the future. Snakes as a source of knowledge is a recurring theme in Greek mythology, although sometimes the snake brings understanding of the language of animals rather than an ability to know the future. Cassandra is a figure of both epic tradition and of tragedy.