1851: A Monograph of the Sub-class Cirripedia, with Figures of all the Species. The Lepadidae; or, Pedunculated Cirripedes. 1851: A Monograph on the Fossil Lepadidae, or, Pedunculated Cirripedes of Great Britain 1854: A Monograph of the Sub-class Cirripedia, with Figures of all the Species. The Balanidae (or Sessile Cirripedes); the Verrucidae etc. 1854: A Monograph on the Fossil Balanidæ and Verrucidæ of Great Britain 1858: On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection (Extract from an unpublished Work on Species)