2 88 THE OSTEOLOGY OF THE REPTILES 



A. Suborder Eusuchia 



An antorbital opening primitively present but lost in many an- 

 cient and all modern forms. Mandible with an external vacuity 

 posteriorly. Nine cervical vertebrae, twenty-three or twenty-four 

 presacrals. No sclerotic plates in orbits. Body with dermal bones. 

 Feet partly webbed, clawed, not paddle-like. 



Until within recent years, and still by some authors, the Eusuchia 

 comprised only those crocodilians with procoelous vertebrae, am- 

 phicoelian forms comprised in the suborder Mesosuchia. It is now 

 known that the change in the form of the vertebrae was a relatively 

 unimportant one and may have occurred in different lines of descent. 



Family Teleosauridae. Vertebrae platycoelous. Internal nares 

 large, situated at posterior end of palatines. Face very long and 

 slender. An antorbital opening sometimes present. Postorbital bar 

 not modified. Upper temporal opening large. A nearly complete 

 dermal armor. Front feet much smaller than hind. From two to 

 ten feet in length. 



Jurassic. Pelagosaurus Bronn, Teleosaurus Geoffroy, Teleido- 

 saurus Deslongchamps, Suchodus Lydekker, Aeolodon Meyer, Cro- 

 codilemus Jourdan, Gnathosaurus Miinster, Europe. Steneosaurus 

 Geoffroy, Europe, Madagascar. 



Cretaceous. ? Teleorhinus Osborn, Wyoming. 



Family Pholidosauridae. Vertebrae platycoelous. Internal 

 nares opening in palatines and pterygoids. Face long; the nasals 

 reach to the premaxillae. Upper temporal opening smaller than 

 orbits. Postorbital bar modified. Front legs larger than in the 

 Teleosauridae. Dorsal and ventral armor present. 



Upper Jura and Lowermost Cretaceous. PhoUdosaunis Meyer 

 (Macrorhynchus), Pterosuchus Owen, Europe. 



Family Atoposauridae. Vertebrae platycoelous. Posterior nares 

 not reaching pterygoids. Head short, broad. Upper temporal open- 

 ings much smaller than orbits. Dermal armor composed of two rows 

 of quadrilateral plates, probably extending on tail. Probably no ven- 

 tral scutes. Tail long. Small reptiles from eight to sixteen inches in 

 length. , 



