262 THE OSTEOLOGY OF THE REPTn.ES 



Protorosaurus in size, slenderness, and proportions. The single- 

 headed ribs are described by Thevenin as articulating intercentrally. 



Lower Permian. ?Aphelosaurus Gervais, France. 



Upper Permian. Protorosaurus v. Meyer, Germany. 



The nares were described by Seeley as immediately in front of 

 the orbits — an error. There may be a small antorbital foramen, 

 but it is doubtful. 



Family Saphaeosauridae. Slender, terrestrial or subaquatic rep- 

 tiles about two feet in length. Skull with a single temporal opening, 

 the quadrate fixed and the lateral temporal region moderately broad. 

 No postf rontals ; postorbitals large. No parietal foramen. Maxillae 

 and dentaries edentulous, with cutting edges. Vertebrae procoelous 

 without intercentra; twenty-three presacrals, two sacrals, and fifty 

 or more caudals. Caudal vertebrae with splitting point (?). Ribs 

 single-headed, articulating with anterior part of centrum. Coracoid 

 with two median emarginations. Interclavicle T-shaped, the clavicles 

 slender. Parasternals numerous, composed of a median unpaired 

 pices and a lateral splint on each side. Pubes and ischia broadly 

 separated by pubo-ischiatic opening, the ischia with a stout posterior 

 tuberosity. An ectepicondylar foramen in humerus. Manus and pes 

 pentedactylate, with primitive phalangeal formula. 



Saphaeosaurus, usually called Sauranodon, has long been classed 

 as a representative of a distinct family of the Rhynchocephalia. The 

 skull, as described by both von Meyer and Lortet, has but a single 

 temporal opening on each side, bounded externally by the postorbital 

 and squamosal (tabular?) . There is no lower temporal opening. The 

 structure of the temporal region as described is doubtful. In much 

 probability the tabular, squamosal, and quadratojugal are all present. 

 In all its essential characters it is a Lacertilian with a primitively 

 fixed quadrate. The vertebrae, as figured and described by Lortet, 

 are procoelous, perhaps the first known evidence of such in geological 

 history. 



Upper Jurassic. Saphaeosaurus v. Meyer {Sauranodon Jourdan), 

 France. 



Family Pleurosauridae. Very slender, snake-like, aquatic rep- 

 tiles, with short neck, long body, very long flattened tail, and small 

 pentedactylate legs; attaining a length of nearly five feet. Skull 



J 



