Is this ? ..
CLOSED: What type of caterpilla? ...
Possibly the larva of the Prometheus Moth, Callosamia promethea or one of the silk worm moths.
This appears to be a caterpillar of the promethea moth - http://www.butterflynature.com/images/-Promethea_caterpillar.jpg
Note that the caterpillar of the tulip tree moth is very similar, but lacks the pale ring around the black spots on the body.