b. Supratemporal small; maxillary firmly attached to posterior extremity of praemaxillary.
Praemaxillary paired; a large hole on each side of the skull, between the post-frontal and the squamosal; basis cranii double; suboperculum absent; ribs sessile .......... 9. Notopteridae.
Praemaxillary paired; basis cranii simple; suboperculum reduced; ribs inserted on parapophyses .......... 10. Osteoglossidae.
Praemaxillary single; basis cranii simple; suboperculum and interoperculum absent; ribs inserted on parapophyses .......... 11. Pantodontidae.
c. Supratemporal small; maxillary movable; ribs sessile; ventral fins below the pectorals .......... 12. Ctenothrissidae.†
B. Supraoccipital separating parietals, or adipose fin present.
1. Interoperculum enormous; symplectic absent; basis cranii simple .......... 13. Phractolaemidae.
2. Interoperculum normal; symplectic present; basis cranii double.
a. Teeth in sockets; maxillary firmly attached to praemaxillary. Symplectic exposed .......... 14. Saurodontidae.†
b. Teeth not in sockets.