INFRACLASS THORACICA DARWIN, 1854

Diagnosis: Monophyletic in all molecular analyses. Body consists of a capitulum raised on a flexible peduncle, or the peduncle secondarily lost; capitulum armed with at least paired scuta–terga; plates may be lost secondarily.

Comment: None of the morphological characters is necessarily an apomorphy compared with the remaining Cirripedia .

In the subsequent taxonomic ranking, taxa containing both fossils and extant species are indicated with †. Taxa with fossil species alone are indicated with ††.