As indicated by the ☞ ICNP in Rule 8, names of ☞ classes should be formed by appending -ia to the stem of the name of the type genus of the type order of the class. However, many ☞ validly published names of classes deviate from this scheme. Either other suffixes were used or the name of the class was not derived from the expected stem. Below the names of classes validly published under the ICNP are listed in groups according to the effective suffix, which is revealed by removing the expected stem from the name. Names of classes that do not contain the expected stem are marked as irregular. See also the LPSN introductory page on forming names.