JURASSIC VERTEBRATE FOSSILS. 501 



The small, elongated head was covered in front by a horny beak. 

 The teeth are confined to the maxillary and dentary bones, and are Dot 

 visible in the figure here given. They are unite small, with compressed 

 fluted crowns, and indicate that the food of this animal was soft, succulent 

 vegetation. The vertebras are solid, and the articular laces of the centra 

 are biconcave or nearly Hat. The ribs of the trunk are massive, and 

 placed high above the centra, the tubercle alone being supported on the 

 elevated diapophysis. The neural spines, especially those of the sacrum 

 and anterior caudals, have their summits expanded to aid in supporting the 

 massive dermal armor above them. The limb bones are solid, and this is 

 true of every other part of the skeleton. The feet were short and massive, 

 and the terminal phalanges of the functional toes were covered h\ strong 

 hoofs. There were five well-developed digits in the fore foot and only 

 three in the hind foot, the first toe being rudimentary and the fifth entirely 

 wanting. 



In life, the animal was protected by a powerful dermal armor, which 

 served both for defense and offense. The throat was covered by a thick 

 skin in which were imbedded a large number of rounded ossicles, as shown 

 in the restoration, PL XXII. The gular portion represented was found 

 beneath the skull, so that its position in life may be regarded as definitely 

 settled. The series of vertical plates which extended above the neck, 

 along the hack, and over two-thirds of the tail, is a most remarkable 

 feature, which could not have been anticipated, and would hardly have 

 been credited had not the plates themselves been found in position. The 

 four pairs of massive spines characteristic of the present species, which 

 were situated above the lower third of the tail, are apparently the only 

 part of this peculiar armor used for offense. In addition to the portions of 

 armor above mentioned, there was a pair of small plates just behind the 

 skull, which served to protect this part of the neck. There'were also, in 

 the present species, four flat spines, which were probably in place below 

 the tail, hut as their position is somewhat in doubt, they are not represented 

 in the present restoration. 



All these plates and spines, massive and powerful as they now are. 

 were in life protected by a thick, horny covering, which must have greatly 



