ACH.] 



BATRACHIA. 



617 



ORDER ARCHEGOSAURIA. 

 FAMILY ARCH^EGOSAURID^E. Brachydectes, Hylerpeton. 



ORDER GANOCEPHALA. 

 FAMILY COLOSTEID.E. Amphibamus, Colosteus, Sauropleura, 



ORDER L/ABYRINTHODONTIA. 



FAMILY BAPHETID^E. Baphetes. 

 FAMILY TREMATOSAURID^B. Cricotus. 



ORDER MICROSAURIA. 



FAMILY DIPLOCAULID^E. Diplocaulus. 



FAMILY EOSAURIDJE. Eosaurus. 



FAMILY MOLGOPHID^E. Molgophis, Pleuroptyx. 



FAMILY PELIONID^E. Hylonomus, Pelion. 



FAMILY PHLEGETHONTIID^. Phlegethontia. 



FAMILY PTYONIID.E. Ceraterpeton, Hyphasraa, Oestocephalus, Ptyonius, 



Thyrsidium. 

 FAMILY TUDITANID.E. Dendrerpeton, Leptophractus, Tuditanus. 



ORDER PELYCOSAURIA. 



FAMILY BOLOSAURID^E. Bolosaurus, Chilonyx, Lysorophus. 



FAMILY DIADECTID^E. Diadectes, Helodectes. 



FAMILY CLEPSYDROPSID^E. Archseobolus, Clepsydrops, Dimetrodon, Ectocy- 



nodon, Embolophorus, Empedias, Metarmosaurus, Pariotichus, Thero- 



pleura. 

 FAMILY EDAPHOSAURID^E. Edaphosaurus, Pantylus. 



ORDER RHACHITOMA. 



FAMILY ERYOPSID^E. Acheloraa, Anisodexis, Eryops, Ichthyacanthus, Trimer- 

 orachis, Zatrachys. 



ORDER URODELLA. 



FAMILY COCYTINID^. Cocytinus. 



ORDER AND FAMILY UNCERTAIN. Chirotherium, Collettosaurus, Nothodon, 

 Ophiacodon, Sauropus, Sphseropezium, Sphenacodon, Thenaropus. 



ACHKLOMA, Cope, 1882, Pal. Bull. No. 35, 

 and Proc. Am. Phil. Soc., p. 455. [Ety. 

 a, without; cheloma, a notch.] Man- 

 dible without angular process; teeth 

 subequal, rather larger anteriorly ; 

 pterygoid bone ending in a free, re- 

 curved edge anterior to the quadrate 

 bone; palatines and pterygoids nar- 



row ; palatal foramen wide , posterior 

 border of cranium entire ; without notch 

 on the external side of the epiotic bone ; 

 vertebrae rhachitomous. Type A. cum- 

 minsi. 



cumminsi, Cope, 1882, Pal. Bull. No. 35, 

 and Proc. Am. Phil. Soc., p, 456, Per- 



