Wesley Thorsson writes: It occurs to me that a number of beginners in taxonomy may be slightly confused by two terms used in this thread: "group": as used in genus-group and species-group. "later established" relating to secondary homonyms. Does this indicate that the date of the specific name was later? Aloha Wes OK. To take them in ascending order: "Species group" includes subspecies, species, and superspecies. The older terms "variety" and "form" are considered to refer to subspecies, unless they are clearly below the subspecific level (e.g., if a form is ranked as belonging to a variety, then the form is infrasubspecific). "Genus group" includes subgenus (section, division, ...), genus, and supergenus. Terms such as "section" are inserted into the classification system in cases where needed for clarity. "Family group" includes subfamily (tribe, ...), family, superfamily. Orders, classes, phyla, and kingdoms are not governed by the Code. That's why we have alternative names for the same classes of mollusks, e.g., Univalvia = Gastropoda; Bivalvia = Pelecypoda = Lamellibranchiata. "Later established" means "validly published at a later date". There are a lot of rules that govern whether a publication is to be deemed as valid and what its publication date is, and the rules have been modified in succeeding editions of the Code. It's pretty complex, and taxonomists who get too involved in the Code sometimes sound more like jurists than scientists. Andrew K. Rindsberg Geological Survey of Alabama