PARASUCHIA 433 



half of the jaws. The neck, back, and tail are covered by two 

 rows of large and broad, closely-jointed bony plates ; smaller 

 plates protect the sides and the ventral surface. The vertebrae 

 are still unknown. 



Aetosaurus ferratus of the Upper Keuper near Stuttgart is 

 the best known. One of the greatest treasures of the Stuttgart 

 Museum is a slab of sandstone, about 2 square yards in size, upon 

 which lie huddled together twenty-four individuals of various 

 sizes, the largest measuring 86 cm. or 2 feet 10 inches. They 

 are in a beautiful state of preservation, and many of them are 

 in the most life-like attitudes, just as if a mass of sand had 

 fallen upon them and crushed them down, and as if they were 

 struggling to get out. 



Erpetosuclms and Ornithosuchus of the Elgin sandstone seem 

 to be allied forms. 



Order II. PARASUCHIA. 



As the name implies, a collateral branch of the true Crocodilia. 

 They are, like the Pseudosuchia, restricted to the Keuper forma- 

 tion. The vertebrae are mostly biconcave, sometimes with 

 nearly plain, scarcely concave, central joints. The preinaxillae 

 are very long and powerful. The nostrils lie far back, rather 

 near the orbits, on the top of the snout, within the anterior half 

 of each nasal and almost above the choanae. The latter are 

 situated in front of the palatine bones and are divided by a back- 

 wardly directed process of the vomer, which is plainly visible on 

 the roof of the mouth. The palatines and pterygoids leave a 

 wide median space between them. The pterygoids are narrow 

 and have three processes, the antero-lateral of which joins the 

 palatines and the maxillary bones (there being no separate 

 ectopterygoid), the inner joins the basi-occipital, and the postero- 

 lateral the quadrate. 



The orbit is surrounded by the frontal, prefrontal, lacrymal, 

 postorbital and postfrontal, while the strong jugal is excluded. 

 The temporal region shows a lateral and a dorsal foramen ; 

 the latter opens backwards and above the occiput, being bordered 

 in front by the parietal, laterally by the squamoso-occipital 

 bridge. 



The vertebrae are amphicoelous. The first and second 



VOL. VIII 2 F 



