SYSTEMATIC REVISION 65 



Table IV — Continued. 

 Family Diadectida: — Continued. 



Chilonyx. (Only the skull known.) 



1. Cheek teeth unknown, perhaps cuspate. 



2. Skull with coarse sculpture and tuberculate 

 Desmatodon. 



I. Teeth intermediate between Bolosaurus and Diadectes. 

 Dtadectoides. (Only the vertebral column and hind limb known.) Characterized by small size 

 and stout limb bones. 

 Family Bolosauridce. 

 Bolosaurus. 



1. Cheek teeth with a single cusp. 



2. Skull smooth or slightly rugose. 

 Family Nothodontidte (uncertain). 



Nothodon. 



l. Cheek teeth with three cusps. 



Table V. — Contrasting the Characters of Genera of the Suborder Pareiasauria. 

 Family Pariotichidce. 

 Pariotichus, 



1. Skull low and rounded anteriorly, resembling that of the Amphibia. 



2. Orbits large and located near the middle of the skull. 



3. Teeth more sharply conical than in the Captorhinidce, but less so than in the Amphibia. 



4. One or more cheek teeth anterior to the orbit sharply larger than the rest. Incisors not enlarged. 



5. Teeth probably in more than one row in both jaws, but no evidence. 



6. Basioccipital and basisphenoid large and forming a broad plate on the base of the skull. 



7. Supraoccipital plates standing nearly vertical at the back of the skull. 



8. Surface of the skull with fine sculpture. 

 Ectocynodon (very doubtful). 



Distinguished from other members of the family by rectangular interorbital sculpture. 

 Isodectes. 



1. Skull low and rounded anteriorly; amphibian in appearance. 



2. Orbits large, located in the anterior half of the skull. 



3. Teeth more sharply conical. 



4. Indeterminable. 



5. Teeth in more than one row in the lower jaws. Maxillary series not visible. 



6. Basioccipital and basisphenoid not visible. 



7. Supraoccipital plates horizontal in the single specimen. 



8. Bones of the skull with a sculpture of fine radiating lines. 

 Family Captorhinida. 



Captorhinus. 



1. Skull more elevated than in Pariotichus. More acuminate. 



2. Orbits large, in the posterior half or the middle of the skull; looking laterally. 



3. Teeth obtusely conical or blunt. 



4. Maxillary teeth increasing in size to the fourth or fifth and then diminishing. One or all of the 



incisor teeth enlarged. 



T* 1 * 1 



5. I eetn in more than one row in both jaws. 



6. Basioccipital and basisphenoid not enlarged. 



7. Supraoccipital plates vertical at the back of the skull. 



8. Skull with a definite reticulate sculpture. 



9. Scapula, coracoid, and procoracoid united. 



10. Cleithrum present. 



11. Ischium and pubis broad and plate-like. 

 Labidosaurus. 



1. Larger than Captorhinus. Skull broader behind and more sharply acuminate anteriorly. 



2. Orbits large; near the middle of the skull, looking laterally. 



3. Teeth obtusely conical or blunt. 



4. Maxillary teeth not differing greatly in size. 



5. More than one in each jaw (fide Williston). 



