ORDER VIII 



DINOSAURIA 



243 



tibia, and fibula hollow, the cms somewhat shorter than 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 triangular 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 ; VerM- 

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



Stegosaurus tmgulatus, Marsh. Upper Jura 



Fig. 34S. 

 Colorado. 



Re.storation of skeleton, i/,i() (after Marsh). 



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

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

 Isle of Wight. 



Priconodon, 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 Ornithopoda have been described under the 

 names of Struthiosaurus and Danuhiosaurus, Bunzel ; and Craiaeomus, Oligosaurus, 

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

 are supposed to represent a highly specialised group of Stegosaurs. 



Family 3. Ceratopsidae. Marsh. 



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 horn anteriorly, and 

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

 by the parietals and squamosals. An upper toothless beak is formed by the premaxiUae 

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

 Teeth with a divided root fixed in sockets. Vertebrae amphiplatyan ; 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 



