84 AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



Table X. Showing the Characters of the Family Lysorophida and the Genus Lysorophus. 



1. Small, snake-like, limbless (?). 



2. Skull triangular, without temporal fenestrse or parietal foramen. 



3. Anterior nares on outer edge of skull, nearly terminal. 



4. Orbit lateral, incomplete, lower border wanting. 



5. Quadrate inclined forward, bringing the articular surface beneath posterior 



edge of orbit. 



6. Teeth small and conical, none enlarged. 



7. Lower jaw two-thirds the length of skull. 



8. Limbs and girdles absent (.^). 



9. Neural arch free from the centrum and divided into lateral halves. 



Table XI. Showing the Characters of the Suborder Gymnarthria. 



1. Skull completely over-roofed: no temporal foramina, but lower edge of skull 



cut away, as in some turtles. Lyra (Cardiocephabis) and parietal foramen 

 (Gymnarthrus) present. 



2. Quadrate free, not covered by prosquamosal. 



3. Quadratojugal absent and prosquamosal reduced to small size or absent. 



4. Basisphenoid and parasphenoid forming a large plate on lower surface of skull. 



5. Teeth enlarged at posterior end of maxillary series, growing smaller to anterior 



end. 



6. Lower jaw as long as skull. 



Table XII. Contrasting the Characters of the Genera of the Family Gymnarthridcs. 



Cardiocephalus: 



1. Parietal foramen very small or absent. 



2. Lyra present. 



Gymnarthrus: 



1. Parietal foramen large. 



2. Lyra absent. 



Table XIII. Showing Characters of the Family Cricotida and the Genus Cricotus. 



1. Skull elongate, like Archegosaurus in form. 



2. Nares not terminal, near outer edge of skull. 



3. Orbits near middle of skull, looking upward and outward. 



4. Intercentra complete, perforated disks, forming with the similar pleurocentra 



embolomerous vertebrae. 



5. Two Ci) sacral vertebrae, the anterior one with a large rib. 



6. Caudal vertebrae numerous. Chevrons coossified with the intercentra. 



7. Ilium reptilian, with a strong projection to the rear. 



8. A close abdominal armor of imbricate scales. 



