Well, the Almanac is basically supposed to be a map of all the fictional worlds ever. (There are way more matriarchal societies than I ever could have imagined, by the way.) So in his South America section, he describes two islands, both within swimming distance of each other that are unaware of each other. One is the island where Robinson Crusoe lived all by himself for years ... but if only he'd just swum a few miles, he could have been stranded on/gone to Herland.

I thought it was funny, anyway.