This is Loango, a crown male Mangabey monkey, who was rejected by his mother shortly after birth. The baby was born on March 2012 at the Jardin des Plantes's zoo in Paris. He's being hand raised by zookeepers.
Sagui dwarf monkeys, discovered in 1997 in the Brazilian rainforest when a local showed up to a primate orphanage with a baby in a bucket. It's the second smallest monkey species of that particular habitat.