How are Ostariophysi divided into the series Anotophysi and Otophysi?

The superorder Ostariophysi is divided into two series, Anotophysi and Otophysi, based on the presence or absence of a true Weberian apparatus, a bony connection between the swim bladder and the inner ear that enhances sound perception.1

• Series Anotophysi: This group consists solely of the order Gonorynchiformes (such as the milkfish). These fishes do not possess a true Weberian apparatus, though they do have a rudimentary version involving the first three vertebrae and one or more ribs.12
• Series Otophysi: This group includes the remaining four orders: Siluriformes (catfishes), Cypriniformes (minnows, carps, and suckers), Characiformes (characins), and Gymnotiformes (electric eels). Members of this series possess a true, complex Weberian apparatus, which functions as a hearing organ by transmitting pressure changes from the swim bladder to the ear via a chain of ossicles.12