514 L. C. Miall — On Lahyrlnthodonta. 



12. Brachyops, Owen. 



13. Micropholis, Huxley. 



14. Eliinosaurus, Waldheim. 



15. Bothriceps, Huxley. 



ni. — Malacocyla. Skull vaulted, triangular, "with large postero- 

 lateral expansions. Lyra consisting of two nearly straight longi- 

 tudinal grooves, continued backwards as ridges. Orbits large, pos- 

 terior, irregular. Temporal depressions, passing backwards from 

 orbits. No post-articular process to mandible.^ 



* Teeth with large anterior and posterior cutting edges. 



16. Losomma, Huxley. 

 «= * Teeth conical. 



17. Zygosaurus, d'Eichwald. 



IV. — Atheoodonta. Maxillary teeth wanting. Vomerine teeth 

 aggregated. Orbit imperfect. 



18. Batrachiderpeton, Hancock and Atthey. 



19. Pteroplax, Hancock and Atthey.^ 



[V. — An uncharacterized group for the reception of some or all of 

 the following genera.] 



20. Pholidogaster, Huxley. 



21. Ichthyerpeton, Huxley. 



22. Pholiderpeton, Huxley. 



23. Erpetocephalus, Huxley. 



VI. — Akchegosaukia. Von Meyer. Vertebral column notochordal. 

 Occipital condyles unossified. 



24. Archegosaurus, Goldfuss. 



25. Apateon,^ Von Meyer. 



B — Centra of dorsal vertebra elongate, contracted in the middle. 



VII. — Heleothrepta. — Skull triangular, with produced, tapering 

 snout. Orbits central. Mandibular symphysis very long, about 

 one-third of the length of the skull. 



26. Lepterpeton, Huxley. 



VIII. — Nectridea. — Epiotic cornua much produced. Superior 

 and inferior processes of caudal vertebra dilated at the extremities 

 and pectinate. 



27. Urocordylus, Huxley. 



28. Keraterpeton, Huxley. 

 IX. — AiSTOPODA. Limbs wanting. 



29. Ophiderpeton, Huxley. 



30. Dolichosoma, Huxley. 



X. — MiCROSATJRiA, Datvson. Thoracic plates unknown. Ossifica- 

 tion of limb-bones incomplete. Dentine non-plicate, pulp cavity large. 



31. Dendrerpeton, Owen. 



32. Hylonomus, Dawson. 



33. Hylerpeton, Owen. 



1 Loxomma. 



^ The vomerine teetli are unknown, and this genus may therefore require to be 

 removed. 



3 Of doubtful distinctness. 



