At the Guira Oga wildlife rescue center in Iguazu, Argentina, this is the South America Snake-neck Turtle, or in Spanish, Tortuga Cuello de Serpiente. It ranges from here into southern Brazil. www.dixpix.ca/Amazon/fauna/riverlife/index.html
From Holbrook, North American Herpetology, circa 1842 (public domain). This is a modified version of a plate from this work at the Biodiversity Heritage Library. I cropped and cleaned up the image quite a bit--removing the yellow cast and enhancing contrast and color a little. More of these images are posted on Wikimedia Commons, and I will be adding more as time allows.