I realize that this post was made 11 years ago (!) but I don't know if you've already found the answers you sought.
There was a Barnabus Phelps born in Connecticut in 1806 to Theodore and Charlotte Phelps, and he may be the same Barnabus of which you ask. The Phelpses were a long and illustrious Connecticut family; Theodore's 4th great-grandfather, William Phelps (1599-1672) helped found Windsor, CT (and Dorchester, MA), and the Phelpses were prominent in Hartford and its environs for the next couple of centuries. Theodore and Charlotte moved to Brown County, Kansas. I have no idea when Theodore died.
I'm Theodore and Charlotte's 5th great-grandson through their daughter Lois, who married Nicholas Preble Sprague. I'd love to find out what you might know about the family -- particularly Charlotte's maiden name, which I've heard to be "Cofften", but I suspect is slightly misspelled. Please feel free to contact me directly at rch427 at yahoo d0t c0m.