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.
"野尻湖層産カワニナ胎児殼化石について : 現生カワニナとの比較研究 "On the fossil embryonic shell of Semisulcospira libertina (GOULD) (Mesogastropoda: Pleuroceridae) from the latest Pleistocene Nojiri-ko Formation, Nagano Prefecture, Central Japan: A comparative study of recent and fossil Semisulcospira".