A. SUPERORDER DIAPTOSAURIA
Teeth on some or all the palatal bones, acrodont or protacrodont. No antorbital opening; no interparietals or tabulars. Vertebrae amphicoelous. Dorsal ribs holocephalous, articulating in part or chiefly to centrum. Two or three sacral vertebrae. Fifth tarsale absent. Phalangeal formula never reduced. Parasternal ribs present.
In the absence of more complete information as to the structural details of some of the forms included under this group name, and in the differences of opinion, as usual, as to the value of the groups, the tribe or superorder Diaptosauria has a present use. Several groups formerly placed under it are now relegated to other divisions.
14. ORDER RHYNCHOCEPHALIA
Terrestrial or littoral lizard-like reptiles of small or moderate size. Palate primitive, with teeth on some or all the bones. Pectoral girdle complete. Dorsal ribs holocephalous, articulating in intercentral space and arch.
The three groups of reptiles here considered suborders are by some authors given a family rank, by others ordinal. Except the living Sphenodon, most of the genera are yet incompletely known. The differences between them seem hardly greater than among the Lacertilia with the inclusion of the Pythonomorpha.
A. Suborder Rhynchosauria
Skull more or less depressed and broad, with a strong, decurved, and edentulous beak, formed by the premaxillae. Temporal openings relatively large, their boundaries as in the Sphenodontia. No parietal foramen. Nares undivided. Palate with small interpterygoidal opening. Dorsal intercentra absent or unknown. About seven or eight cervicals and twenty-three presacrals; two sacrals. A small pubo-ischiatic vacuity. Humerus without epicondylar foramina.
A small group of terrestrial, perhaps in some cases subaquatic, shore-dwelling and shell-eating reptiles from three to six feet in length. The complete skull, tail, and mesopodials are known in none. In Howesia a distinct intermedium tarsus is figured; if not an
