ORDER I 



RHYNCHOCEPHALIA 



151 



Family 5. Sphenodontidae. 



Vertebrae amphicoelous, sometimes with persistent noto- 

 chord ; intercentra present in cervical and caudal regions. 

 Premaxillae each with a small pointed tooth. A single 

 series of depressed, triangular, acrodont teeth present on 

 maxillae, mandibles, and outer edge of the palatines ; vomer 

 toothless. External nares separated ; interclavicle T-shaped; 

 dermal scales subrectangular. Upper Jura to Recent. 



Homaeosaurus, v. Meyer (Sapheosaurus, v. Meyer), 

 (Fig. 241). Attaining a length of between 20 and 40 

 cm., and differing from the recent Sphenodon in that 

 intercentra are absent between the dorsal vertebrae 

 ribs without uncinate processes, and humerus not 

 pierced by entepicondylar foramen. Mandibular rami 

 united at the symphysis by ligaments ; second sacral 

 rib bifid distally. Upper Jura (Lithographic Stone) ; 

 Bavaria, and Cerin, France. Kimmeridgian of Hanover, 

 and Purbeckian of England. H. maximiliani, v. Meyer. 



Ardeosaurus, Acrosaurus, v. Meyer ; Euposaurus, 

 Jourdan. Upper Jura (Lithographic Stone) ; Bavaria, 

 and Cerin, France. 



Pleurosaurus, v. Meyer (Anguisaurus, Miinst. ; Sauro- 

 phidium, Jourdan). Body serpentiform, upwards of 

 1*5 m. long, the tail forming one-third the total length. 

 Snout tapering in front. Presacral vertebrae with 

 stout single-headed ribs ; abdominal ribs well developed. 

 Fore-limbs shorter than the hinder pair. Upper Jura 

 (Lithographic Stone) ; Bavaria, and Cerin, France. P. 

 muensteri, Wagner. 



Sphenodon, Gray (Hatteria, Gray). Inferior 

 border of the large orbits formed by maxilla 



external nares divided ; a single tooth on either 





Fig. '241. 



Homa&osaurus pulchellus 

 Zittel. Upper Jura ; Kel- 

 heim, Bavaria. Ventral 

 aspect, Vo. 



side of the premaxillary beak ; intercentra present 



between all the vertebrae, humerus with both entepicondylar and ectepicondylar 



foramina or grooves. 



Recent, inhabiting certain islands off New Zealand. 



VERTICAL RANGE OF THE RHYNCHOCEPHALIA. 



