These bright and beautiful barnacle illustrations are from a monograph of Darwin’s from 1851, Living Cirripedia. Barnacles, along with fancy pigeons, were an extremely important group to Darwin’s work, and he spent eight years studying them in minute detail and reclassifying the entire group. His studies, which interrupted to some extent his writing of On the Origin of Species, also helped to cement some of his ideas about homology and heredity through comparisons across the anatomy of his countless extant and fossil specimens.
Read more about Darwin’s work on barnacles here.
Extant: A living (as opposed to extinct) organism or group.
Homology: Similarity due to common ancestry.