ACH.] 



BATRACHIA. 



617 



Order Archegosauria. 

 Family Arch^kgosaurid^e. — Brachydectes, Hylerpeton. 



Order Ganocephala. 

 Family ColosteiD;E. — Amphibamus, Colosteus, Sauropleura. 



Order L,abyrinthodontia. 



Family BaphetidjE. — Baphetes. 

 Family Trematosaurid^e. — Cricotus. 



Order Microsauria. 



Family Diplocauldxe. — Diplocaulus. 



Family Eosaurid^e. — Eosaurus. 



Family Mo-LGOPHiDiE. — Molgophis, Pleuroptyx. 



Famdly Pelionid^e. — Hylonomus, Pelion. 



Family Phlegethontiid,e. — Phlegethontia. 



Family Ptyoniid^e. — Cera terpe ton, Hyphasraa, Oestocephalus, Ptyonius, 



Thyrsidium. 

 Family Tuditanid;e. — Dendrerpeton, Leptophractus, Tuditanus. 



Order Pelycosauria. 



Family Bolosauridte. — Bolosaurus, Chilonyx, Lysorophus. 



Family Diadectdle. — Diadectes, Helodectes. 



Family Clepsydropsdxe. — Archseobolus, Clepsydrops, Dimetrodon, Ectocy- 



uodon, Embolophorus, Erapedias, Metarmosaurus, Pariotichus, Thero- 



pleura. 

 Family Edaphosaurid^e. — Edaphosaurus, Pantylus. 



t Order Rhachitoma. 



Family Eryopsid^e. — Achelorna, Anisodexis, Eryops, Ichthyacanthus, Trimer- 

 orachis, Zatrachys. 



Order Urodella. 



Family Cocytinid.e. — Cocytinus. 



Order and Family Uncertain. — Chirotherium, Collettosaurus, Nothodon, 

 Ophiacodon, Sauropus, Sphaeropezium, Sphenacodon, Thenaropus. 



Acheloma, 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- 

 mian. 



