Raymond L. Ditmars, a friend of Marianne Moore, was the curator of the New York Zoological Garden for many years.  Moore said that she learned about the hopping desert rodent, the jerboa, from Ditmars' 1931 book, Strange Animals I have Known; in it, he writes, "There are remarkable forms of adaptation.  There are little rats called jerboas which run on long hind-legs as thin as a match.  The forelimbs are mere tiny hands.  They are fleet and coloured like the sand.  They have a long balancing tail, with decorative pad of black and white fur at the tip.  This tip is, in fact, more than decorative, as the pad is like a little snow-shoe to keep the end from sinking in the sand.  The tail is carried in upward curve when the creatures run.  When they stop it is rested on the ground so that the whole body is little tripod.  The feet have furry pads to prevent their becoming imbedded in the soft sand.  I kept one for several years, not giving it a drop of water.  It fed on dry corn and loved stems of dry grass.  The only moisture it had came from occasional bits of greens, of which it was not over fond."