Posted By:
AndyAs stated above, the symbol does mean Copyright International Feature Service and it also appears on a few other issues. This set uses the same images as the W572 set and they also have this symbol. It's interesting to note that the symbol does not always look like the one pictured on Ty's card. Sometimes it is a regular (c) with IFS following it, but it still means the same thing.
William Randolph Hearst started the International Feature Service in 1912 to syndicate comic strips that were popular at the time. It was later renamed King Features and, I believe, is still around today.
Thanks,
Andy