Gillian Houghton 
Turtles [PDF ebook] 

Did you know that the turtle’s top shell is an outgrowth of bone, and the scales on it are made of the same substance that forms our finger nails? Or that its nostrils are placed high on its head so that it can breathe without raising its head far above water? This fascinating book reveals these, and many little-known details about the turtle’s body, inner working, geographical adaptations, genealogy, history, and endangered future.