It is a condition characteristic of the Mesogastropoda and Neogastropoda, and is the obverse of the more-primitive hypoathroid condition in which the pleural and pedal ganglia lie close together under the animal's gut and communicate with the cerebral ganglia via long connectives.
It is a condition that is characteristic of the Archaeogastropoda clade, and is the inverse of the evolutionarily more recent epiathroid condition, characteristic of the Mesogastropoda and Neogastropoda, in which the pleural, pedal, and cerebral ganglia all lie close together.