Are there demons in the ceiling coffers of leonardo di vinci's the last supper?

The Sforza family coat of arms is painted on the ceiling. There doesn't seem to be a devil, but snakes. Here is a link a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Coat_of_arms_of_the_House_of_Sforza.svg/420px-Coat_of_arms_of_the_House_of_Sforza.svg.png" rel="nofollow"http://upload.wikimedia.org/wikipedia/co…/a