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 ; Vecti- 

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



Stegosaurus ungulatus, Marsh. 



Fig. 34S. 

 Upper Jura ; Colorado. Res toraticn of skeleton, !/60 (after .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. 



Prkonodon, 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 Danubiosaurus, Bunzel ; and Crataeomus, 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 frontal s, a median nasal horn anteriorly, and 

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

 by the parietals and squamosals. .In upper toothless beak is formed by the premaxilhic 

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

 Teeth with a divided mot fixed in sockets. Vertebrae amphiplatyan ; >/m-s<il centra 

 extremely short. Limbs nearly equal; jive 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 



