Carapace

Upper shell of Crabs and of Turtles. In the latter, made up of a median series of neural plates developed from the spinous proce es of the vertebræ, flanked on each side by eight costal plates largely made up of the expanded ribs, and finally around the edge a row of marginal plates, the anterior median one being the nuchal, the posterior, the pygal. These are all overlaid by a corresponding series of epidermal scutes, the vertebral members of the series being but half as numerous.