Who was Charles Baskerville's next of kin?

In Sir Arthur Conan Doyle's novel, The Hound of the Baskervilles, Mr. Sherlock Holmes and Dr. John Watson have been asked by Dr. Mortimer to look into the death of a good friend. Sir Charles Baskerville recently died under somewhat mysterious circumstances. Sir Charles was in generally good health and took a walk every evening, but one night he didn't come back. His body was found at the end of the lane, surrounding by giant dog prints—it appeared he had simply died of fright. For many years, a curse has surrounded the Baskerville family and it seems that the spectral hound which killed Hugo Baskerville more than a century prior is back at it again.

In the event of Sir Charles' death, his estate falls into the hands of his next of kin—his nephew Sir Henry Baskerville. After Sir Henry, the next in line would be his estranged cousin who goes by the name of Stapleton.