Il62 



CLASS REPTILIA. 



Jurassic of North America ; but it appears that certain forms from the 

 Oxford and Kimeridge Clays of England, described at an earlier date 

 under the preoccupied name of Omosau?us, are not entitled to gen- 

 eric distinction. These Dinosaurs agree with the Scelidosauridce. in 

 the general structure of their teeth, and the possession of a dermal 

 armour of scutes and spines, as well as in their solid limb-bones ; 

 but differ by the great height of the neural arches of the vertebrae, 

 as well as by the circumstance that in the sacrum each arch is 

 either chiefly or entirely supported by a single centrum, instead of 

 by the adjacent portions of two centra, as in the preceding families. 

 The skull (fig. 1062) shows many points of resemblance to that of 

 Iguanodon, especially in the presence of a predentary bone ; but it 

 is lower and narrower, and thereby approximates to the Scelido- 



Fig. 1062. — Left lateral view of skull of Stegosatirus stenops ; from the Upper Jurassic of 

 North America. One-quarter natural size, a, Nares ; b, Orbit ; c, Infratemporal fossa ; pm, 

 Premaxilla ; m, Maxilla ; n, Nasal ; pf, Prefrontal ; so, Supraorbital ; fp, Postfrontal ; po, Post- 

 orbital ; /, Lachrymal ; j, Jugal ; q, Quadrate ; sq, Squamosal ; oc, Occipital condyle ; ar, Arti- 

 cular ; sa, Surangular; an, Angular; s, Splenial ; d, Dentary ; pd, Predentary. (After Marsh.) 



saurian type. The Iguanodont resemblance is, however, so marked 

 as to forbid the reference of the forms with dermal armour to a 

 separate suborder. The two rami of the caudal chevron-bones do 

 not unite superiorly. In the pelvis (fig. 1063) the ilium has an 

 enormous preacetabular process, and a very short postacetabular 

 portion ; while the ischium and pubis are relatively short. In the 

 femur (fig. 1063) the inner trochanter is either very small or 

 absent; the metatarsals are very short and stout; and the five 

 digits of the plantigrade pes approximate in contour to those of 

 the Elephant. The tibia and fibula are suturally united together at 

 their extremities ; and the former is completely joined to the astra- 

 galus, and the latter to the calcaneum. Other peculiar features of 

 these remarkable reptiles are to be found in the structure of the 



