8o AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



Table III. Contrasting the Characters of the Families of the Rhachitomous 

 Division of the Temnospondyli. 



I. Eryopida: 



1. Small to large, reaching a length of from 2 to 2.5 meters. 



2. Occipital condyles distinct. 



3. Otic notch small. 



4. Parasphenoid large, joining a basioccipital posteriorly. 



5. A single sacral rib. 



6. No dermal armor on the back. 



7. Clavicle and interclavicle without sculpture. 



8. Cleithrum present. 



9. Humerus heavy; ends at right angles to each other; prominent processes present. 

 ID. Femur with a prominent narrow ridge on ventral surface. 



11. The two sides of the neural spine united. 



12. Intercentra thick and heavy, nearly closing the notochordal canal. 



II. Trimerorhachida: 



1. Small, not over 5CXD centimeters long. 



2. Occipital condyles united. 



3. Otic notch small. 



4. Parasphenoid large. Basioccipital not apparent. 



5. Two functional sacral ribs (?). 



6. No dermal armor on back. 



7. Clavicle and interclavicle with external sculpture (.?). 



8. Unknown. 



9. Humerus small, without condyles. Articular ends nearly parallel; without 



prominent processes. 

 ID. Femur without ridge on ventral surface (.''). 



11. The two halves of the neural spine separate. 



12. Intercentra very thin, leaving a large notochordal space. No processes on the 



intercentra for the rib. 



III. Dissorhopliida: 



1. Small, not over 500 centimeters long. 



2. Occipital condyles separate. 



3. Otic notch represented by a large fenestra. 



4. Parasphenoid reduced to a slender rod. 



5. Two functional sacral ribs. 



6. Dorsal armor composed of the laterally expanded neural spines smooth on 



upper surface, overlain by narrow dermal plates, which alternate with the 

 spines in position. 



7. Clavicles and interclavicle small, without sculpture. 



8. Cleithrum very large. 



9. Unknown. 

 ID. Unknown. 



11. The two halves of the neural spine united. 



12. Intercentra thick, constricting the notochordal space. No processes on inter- 



centra for the ribs. 



IV. Aspidosauridce: 



1. Small, not over 500 centimeters in length. 



2. Occipital condyles separate. 



3. Otic notch small. 



4. Unknown. 



5. Unknown. 



6. Apices of neural spines expanded, with a rough sculpture on the upper surface. 



No overlying dermal plates. 



7. Unknown. 



8. Unknown. 



9. Unknown. 

 ID. Unknown. 



11. The two halves of the neural spine united. 



12. Intercentra thick, constricting the notochordal space. Lateral processes for 



the head of the rib present. 



