Because the cats would have eaten it, that's why. But there was a MARMOSET on the loose in East Palo Alto! Nobody knows where he came from, but he's about to head out to Primarily Primates in Texas. ("Tiny Monkey Found in Peninsula Yard," SFChron, Jun 30, 06)
That facility deserves mention: it's a nonprofit, 75-acre outpost that cares for surplus zoo animals, lab experiment refugees (like chimps used in Air Force experiments), unwanted pets and rejected animal acts. They do a LOT of last-minute rescues of huge primate colonies. Unfortunately, Primarily Primates does not take online donations right now, but there is an address at the bottom of every page. Please check it out.