What is "trionychidae"

The Trionychidae are a taxonomic family of a number of turtle genera commonly known as softshells. They are also sometimes called pancake turtles (although they are distinct from the pancake tortoise). Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly brackish areas. Members of this family occur in Africa, Asia, and North America. North American members of genus Trionyx were fairly recently (1987) assigned the resurrected genus name Apalone by Meylan, though they are still listed semicorrectly as Trionyx in some texts.