ANOMODONTIA. 



373 



mens attain a great size. Pliosaurus is confined to the Middle 

 and Upper Oolites. 



ORDER VII. ANOMODONTIA. The members of this order 

 are especially characterised by the structure of the mouth, the 

 jaws being converted into a kind of beak, which was pro- 

 bably sheathed in horn, and resembled the jaws of a Turtle. 

 Sometimes the mouth appears to have been wholly destitute 

 of teeth, but in other cases there was a single pair of teeth 

 implanted in the upper jaw, growing from persistent pulps, 

 and assuming the character of great tusks. The dorsal verte- 

 brae are biconcave, and the anterior trunk-ribs have bifurcate 

 heads. The sacrum is large, composed of several vertebrae. 

 The animal seems to have been organised for terrestrial pro- 

 gression, the pectoral and pelvic arches being strong, and the 

 limbs well developed. 



By Owen the genera Dicynodon, Oudenodon, and Rhyncho- 

 saurus are included in this order; but the last of these is 

 regarded by Huxley as a Lacertilian. In Dicynodon (fig. 323, 



Fig. 323. A, Skull of Dicynodon lacerticeps, showing tfie maxillary tusk. B, Skull 

 of Oudenodon Bainii. From the Trias of South/ Africa. (After Owen.) 



A), the anterior portions of the jaws appear to have been al- 

 together toothless j and they form a kind of beak, which was 

 probably sheathed in horn. The lower jaw has no teeth ; but 



