WHAT THEY ARE
The Shaw's Jird (Meriones shawi) is about the same size as a rat and looks like a giant version of the Mongolian Gerbil. Indeed, the two species are closely related. They both belong to the same branch of the gerbil family, The Jirds. The Mongolian Gerbil is in fact not a true gerbil at all but a jird. Its proper name is the Clawed Jird (Meriones unguiculatus).
Click for article - Also has a chart showing the different types of Jirds.