I have collected a fair number of Contraconus species. The problem of separating these species is, in part, due to their very limited known range in time and space. Normally a species is separated from its parent by a time gap (so they are not alive together except for a short time) or a geographic gap (such as both sides of the Panama Isthmus). But sometimes they were together for a short time, in the same place, and there were some intergrades at that time and place. When you are dealing with the south Florida fossils, you often are seeing the time and place of the splitting off of the new species, as well as material mixed in from earlier and later times (due to dredging operations) and from disparate environments which may have supported separate species. Thus you will often find a few shells that seem to be in between species. But if you think it through, that is what you would expect to find under the circumstances. Since you are dealing with fossils, you cannot use DNA or allozyme testing to see if the separate forms are really separate species. You cannot tell if you have two slighty overlapping populations or one population with two common forms (ecophenotypes or the like). Remember that a fossil collection, even from a small area, will cover a long time period, much much longer than collections of recent species. And in southern Florida, the environment changed locally quickly too (as the sea level went up and down over the centuries/millenia.) Ed Petuch is a splitter, but for fossil forms it is more easily justified. We will never know which distinct form species were realy just varieties, so you gain in precision by splitting them(although sometimes you go nuts trying to decide which species it is--but aren't some modern species like that?) Some of Petuch's cone species I cannot agree with (as they seem to represent extremes within a seemless population), but the Contraconus species complex seems real, and the names are useful. If you would like, call them all subspecies of C. adversarius (Conrad, 1840). They all are monophyletic, as was noted. C. heilprini and C. mitchellorum, both Petuch,1994, are from his Griffin Pit Fauna of the Okeechobee Formation, which is the topmost (last deposited, in a few restricted areas or only preserved in a few areas) strata in the Caloosahatchee Formation, thus basal Pleistocene (Calabrian), or roughly 1 1/2 million years old. There are no Contraconus species known from younger strata. They apparently perished with a lowering of sea level, destroying their protected and restricted environment. Allen Aigen :-) [log in to unmask]