This link (http://springerlink.metapress.com/app/home/contribution.asp?
wasp=pgwlnnwvmg6ye1lp8fvk&referrer=parent&backto=issue,5,7;
journal,9,29;linkingpublicationresults,1:104918,1) seems to say that S. volucella had its name changed to G. volans. You have to have a subscription to read the whole thing but this was available from the Google abstract:

… caused the name of the North American squirrel to change from Sciuropterus volucella (Pal-. las, 1778) to Glaucomys volans (Linnaeus, 1758). …

Great squirrel picture, by the way.