ORDER DINOSAURIA. 1 1 55 



slenderness and relative length of the pubis and ischium (figs. 1052, 

 1060); the avian characters of the femur, which has a large inner 

 trochanter; the digitigrade hind-foot, furnished with either three 

 or four digits and more or less elongated metatarsals ; and the 

 short pectoral limbs. The bones usually referred to the sternal 

 region are typically hatchet-shaped, and have been regarded by 

 some authorities as clavicles, although it seems more probable that 

 they are connected with the xiphisternum. The cervical vertebras 

 were usually opisthoccelous ; and the rib-facets in the middle dorsal 

 region were placed on the arch. The teeth (figs. 1054, 1055) were 

 arranged in a single row, and are very peculiar and characteristic. 

 Thus they have flattened, diamond-shaped crowns, bearing strongly- 

 marked serrations on the anterior and posterior borders, and one 



Fig. 1056. — Tgnanodon bernissartensis. The skeleton ; from the Wealden of Belgium. 

 About 7 X T natural size. The scale indicates metres. (After Dollo.) 



or more vertical ridges, some of which may themselves be serrated, 

 on their outer aspect. The mandible, again, presents the peculiar 

 feature of having a horse-shoe-like predentary bone at the extremity 

 of the symphysis (fig. 1059). This predentary ossification is devoid 

 of teeth ; while the mandibular symphysis itself is deeply chan- 

 nelled. The family ranges from the Middle Jurassic to the Weal- 

 den and Neocomian of Europe ; its members generally showing a 

 gradual increase in size from the lower to the higher horizons. 

 Like the members of the preceding family, the Iguanodonts habitu- 

 ally supported themselves on the hind limbs, as in the accompany- 

 ing figure. 



