Paul, The ICZN (International Code of Zoological Nomenclature) applies to species-group, genus-group, and family-group names, but not to higher taxa such as orders, classes, phyla, and kingdoms. The rules have mainly to do with the formation of names, validity of names, allowable changes in names (spelling, synonyms, homonyms), designation of the correct author and date of publication, and designation of types. They deal with names rather than real objects, in that you can understand a great deal about nomenclature without picking up a specimen. Nomenclature does not depend on knowledge of genetics, cladistics, or morphometrics, or even on simple observation. This is the distinction between nomenclature (classification of names) and taxonomy (classification of taxa). Species-group names include subspecies, species, and other ranks as needed such as superspecies. Ranks below the subspecies are excluded. Names originally proposed as forms or varieties are automatically considered to be subspecies if possible. Genus-group names include subgenera, genera, and other ranks as needed, such as sections and supergenera. Usually the extra ranks are needed only for genera with large numbers of species, or in some cases for cladistic analysis. Family-group names include tribes, subfamilies, families, and superfamilies, as well as any other ranks that are deemed necessary, such as subtribe. When someone names a new taxon, the other ranks in the same group are automatically generated, so that publication of family "Alabamidae Rindsberg, 1999" would automatically generate subfamily Alabaminae Rindsberg, 1994 and superfamily Rindsberg, 1994 if those taxa are needed. All share the same type genus. Likewise, the new genus "Alabama Rindsberg, 1999" automatically generates subgenus Alabama Rindsberg, 1999 with the same type species; and the new species Alabama alabamiensis Rindsberg, 1999 generates subspecies Alabama alabamiensis alabamiensis Rindsberg, 1999 with the same type specimen. (Whew.) These extra names may never be used, but their virtual existence fends off the proposal of numerous superfluous names by authors trying to immortalize themselves by filling in the gaps between ranks. Besides, it's easier to remember that the Alabaminae belong in the Alabamidae, for the subfamily that contains the type genus Alabamia. The ICZN requires that all family names end in -idae, and all subfamily names in -inae. It also recommends the endings -oidea for superfamilies and -ini for tribes. Now, every family must be named for its type genus. The Latinized suffix -idae is added strictly to the stem of the name of the type genus. Determining the correct stem can be tricky, since the nominative case commonly has a slightly abbreviated or modified form of the stem. Let's go through that some other day. In most cases, you remove the ending -a, -us, or -um and then add -idae, e.g., Alabama > Alabamidae, but Alabamia > Al abamiidae. The stem of Pecten is Pectin- (nominative pecten, genitive pectinis), so the family is Pectinidae, which is the source of much confusion among editors. What happens if the family is named for a genus that is later found to be a junior synonym? Well, after 1960, the rule has been that the family still has the same type genus, even if that name is no longer the correct one, so the old family name remains in use. For instance, suppose it turns out that my new genus Alabama is a synonym of Floridia Dall, 1890. Alabama remains the type genus of Alabamidae, but we relabel our specimens of Alabama as Floridia. But if anyone had already named a family Floridiidae, then Alabamidae would be a junior synonym of that, and both Alabama and Alabamidae would fall into disuse. The rule was different up through 1960, and we still use the old rule for old taxonomic revisions. Someone could replace Alabamidae with a younger synonym Florididae then, and if the name Florididae gained general acceptance, the younger name is maintained. Yes, it is confusing to have different rules for taxonomic revisions done before and after December 31, 1960, but the ICZN deems that this is the best way to maintain stability of established names while revising the rule to make better sense in the future. And everyone who keeps their labels up to date likes stability of nomenclature. Andrew K. Rindsberg Geological Survey of Alabama