PRE-JURASSIC TETRAPODS. 179 



Epipodials long and separated. Caudal region not much 

 deflected. 



Fam. Mixosauriisle. With five digits. 



Mixosaurus. M. Trias, Italy, Germany, Spitzbergen, 



W. IS. America. 



Fam. ShastasauriNjE. Narrow paddles with three or four digits. 



Cymbospondylus. 

 Toretocnemus. 



Merriamia. !> M. Trias, Nevada. 



Shastasaurus. 

 Delphinosaurus. -J 



Super-Order ARCHOSAURIA. 



Reptiles with a skull with two temporal openings. Brain-case 

 much narrowed between the ears, usually surrounded by bone in 

 advance of the prootic. Paroccipital process antero-posteriorly 

 compressed and long, with the fenestra ovale opening on its 

 lower edge. 



A single coracoidal element. 



Order Thecodontia. 



Primitive Archosaurians with clavicles and an interclavicle. 

 Pelvis " plate-like." 



Family " Eosuchidje." 



Thecodonts with intercentra throughout the column. 



" Eosuchus" Watson. U. Permian, S. Africa. 

 Youngina Broom. ,, „ 



Family ErythrosuchiDtE, nov. 



Very large semiaquatic Thecodonts with a twisted humerus' 

 with much expanded ends. Anterior margin of pubis suddenly 

 deflected. Feeble dorsal armour. 



Erythrosuchus Broom. M. Trias, S. Africa. 



Family Phytosaurums McGregor. 



Large Thecodonts, with an elongated rostrum formed mainly 

 by the premaxilla. Dorsal and ventral scutes. 



Mesorhinus Jaekel. L. Trias, Germany. 



Pakvorhinus Williston. M. ? Trias, Wyoming. 



Phytosaurus Jaeger. U. Trias, Wiirttemberg and U.S.A. 

 Mystriosuchus Fraas. ,, ,, 



Rhytidodon Emmons. ,, U.S.A. 



1Stago?iolepis Agassiz. M. Trias, Scotland. 



