My guess is that this is a Spotted Salamander, a fairly common species in your area. The one you have may not perfectly match the one in our photograph, but the pattern of yellow spots varies from one individual to another, and so you should compare the overall shape and size to our description. This poor creature probably found its way into your basement through cracks, drainpipes, or some other opening. He would like to be released into a wooded area where he can find his way underground before it gets too cold. Try to convince your son that wild salamanders make lousy pets: they like to hide in dark places, they sometimes refuse to eat, and the more they are handled the more likely they will get skin diseases and die as a result.