The evolutionary diversity of barnacles, with an updated classification of fossil and living forms Author Chan, Benny K. K. Author Dreyer, Niklas Author Gale, Andy S. Author Glenner, Henrik Author Ewers-Saucedo, Christine Author Pérez-Losada, Marcos Author Kolbasov, Gregory A. Author Crandall, Keith A. Author Høeg, Jens T. text Zoological Journal of the Linnean Society 2021 2021-02-25 193 789 846 journal article 3656 10.1093/zoolinnean/zlaa160 40324061-d8e8-4cfa-9151-4d7b110cff12 0024-4082 5637275 A77C1793-B652-41CE-BB27-CD2E29DEB201 † ORDER BALANOMORPHA PILSBRY, 1916 Diagnosis: Monophyletic in molecular analyses. A peduncle is absent at all stages of development; shell wall made up of four to eight plates, plesiomorphically comprising rostrum, carina, rostromarginals, marginals and carinomarginals.The body is covered by an operculum formed by the paired scuta–terga; the operculum articulates with the wall plates and forms a watertight cover over the mantle cavity. The structure of the wall plates and articulation with the basis is often complex in more derived balanomorphs; the apicobasal (longitudinal) septa are composed of a frond-like array of calcite crystals in cross-section, called an interlaminate figure. Comment: In some forms, the wall is surrounded by one or more whorls of small-sized imbricating scales, as also seen in the Brachylepadomorpha .