ORDER VIII 



DINOSAURIA 



243 



tibia, and fibula hollow, the crus somewhat shorter thaii the femur and not 

 fused with proximal tarsals. Hind foot functionally tridactyle. the hallux 

 reduced, and digit No. v wanting ; phalangeal formula 2, 3, 4, 5, 0. Dermal 

 armour of longitudinal series of small tubercles and triangulär or conical 

 scutes covering the back and tail. S. harrisoni, Owen, attains a length of 4 m. 

 Lower Lias ; England. 



Echinodon, Owen. Purbeckian ; England. Hylaeosaurus, Mantell ; Fedi- 

 saurus, Hulke ; Stenopelix, v. Meyer. Wealden. All imperfectly known. 



7]i /'' 



Fig. 348. 

 Stegosaurus ungulatus, Marsh. Upper Jura ; Colorado. Restoration of skeleton, Viio (aftpr Marsh). 



Polacanthus, Owen. Lumbar-sacral region completely encased in a con- 

 tinuous shield of fused plates, which press the ilium downwards. Wealden ; 

 Isle of Wight. 



Friconodon, Marsh. Founded on detached teeth from the supposed Upper 

 Jura of Maryland. 



From the Upper Cretaceous of Austria and North America a number of 

 fragmentary remains of armoured OrnitJiopoda have been described under the 

 names of Struthiosaiirus and Danubiosaurus, Bunzel ; and Crataeomus, OligosauruSy 

 and Hoplosawus, Seeley, etc. Like the members of the following family, they 

 are supposed to represent a highly specialised group of Stegosaurs. 



Family 3. Ceratopsidae. Mareli. 



Skull of enormous size, wedge-shaped in form, very narrow in the facial portion, 

 with two very large pointed horns on the frontals, a median nasal hörn ariteriorly, and 

 a row of sharp projedions around the margin of the posterior hood, which is formed 

 hy the parietals and squarnosals. An upper toothless beak is formed by the premaxillae 

 together with a median " rostral " bone corresponding to the predentary of lower jaw. 

 Teeth with a divided root fixed in socket s. Vertebrae amphiplat yan ; dorsal centra 

 extremely short. Limbs nearly equal ; five hoofed digits in the fore-, three in the hind- 

 foot. Dermal armour imperfectly known. 



Most of the forms here included attain gigantic proportions, and are 



