In addition to the spelling problems, already well-addressed on this thread, the status of type designations for the genus has been confused.  Thus, the Treatise on Invertebrate Paleontology lists a different species as the type of Isognomon and provides Isogonum as a subgenus based on I. isognomum (for which I did not check the spelling before writing my previous posts).  Recent references have accepted the validity of the designation of I. isognomum as the type of the genus, which makes Isogonum an objective synonym of Isognomon, as well as being a confusingly similar name.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa