Dinusauria — Ornithopoda. 



17 



In Thecodontosmirus platyodon (Fig. 18, d), the teeth have -v^all-case 



oblique serrations on both borders. The ilium is of the Mega- No. 7. 



losaurian type. Remains of this genus are met with in the Table-case, 



Upper Trias, Durdham Down, Clifton, near Bristol, in Glouces- °" 

 tershire. 



Sub-order 3. — Ornithopoda (Bird-footed). 



This sub-order is taken to include the Stegosauria of Marsh. ^^ 4'*^^®®' 



The genus Stegosaurus was originally described by Marsh 

 from the Upper Jurassic of North America, but certain forms 

 from the Oxford and Kimmeridge Clay of England, described 

 under the 2:)reoccupied name of Omosaurus, cannot be separated 

 generically from Stegosaurus. They also agree with the Scelido- 

 sauridce in the general structure of their teeth and in the 

 possession of a dermal armour of scutes and spines, as well as 



Fig. 19. — The left pectoral and pelvic girdles and limbs of Stegosaurus ungulatus 

 (Marsh), from the Upper Jurassic of Southern Colorado, North America (Jj nat. size), 

 s, scapula; c, coracoid ; h, humerus; :■, radius; m, ulna; l-V, phalangeals; U, 

 ilium; is, ischium; p, p\, pubis; /, femur; t, tibia; /I, flbula ; a, astragaius; 

 c, calcaneum (after Marsh). 



in their solid limb-bones. The neural arches of the vertebrae 

 are very much higher, and in the sacrum each arch is chiefly^'or 

 entirely supported by a single centrum, instead of by the 

 adjacent portions of two centra as in the Ornithopoda. 

 (1876) .3 



