In the book "Hound of the Baskervilles", what is Stapleton's first name?

Rodger Baskerville Jr.
("My inquiries show beyond all question that the family portrait did not lie, and that this fellow was indeed a Baskerville. He was a son of that Rodger Baskerville, the younger brother of Sir Charles, who fled with a sinister reputation to South America, where he was said to have died unmarried. He did, as a matter of fact, marry, and had one child, this fellow, whose real name is the same as his father's.")