I think that this is the bookplate of George Henry Lane-Fox Pitt-Rivers, who was an eugenicist. The hyphens and lack of a surname, is rather confusing. If this is his bookplate, then he had it designed when he was only 19y.
Plate size: trimmed
Design: 91 x 73 mm max.
Credit: W.P.B. (William Phillips Barrett)
Designer: Robert Osmond (Lee, 1998: 398)