Dinosauria — Ornithopoda. 1 7 
In Thecodontosaums platyodon (Fig. 18, d), the teeth have 
oblique serrations on both borders. The ilium is of the Mega- 
losaurian type. Remains of this genus are met with in the 
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. 
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 preoccupied name of Omosaurus, cannot be separated 
genet ically from Stegosaums. 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 
in their solid limb-bones. 
Fig. 19.— The left pectoral and pelvic girdles and limbs of Stegosaurus ungulatus 
(Marsh), from the Upper Jurassic of Southern Colorado, North America (J* nat. size), 
s, scapula; c, coracoid; h, humerus; r, radius u, ulna; 1-F, phalangeals; if, 
ilium; is, ischium; p, pi, pubis; /, femur; t, tibia; j 1, fibula; a, astragalus; 
c, calcaneum (after Marsh). 
The neural arches of the vertebra; 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. 
(1189) 3 
Wall-case, 
No. 7. 
Wall-case, 
No. 4. 
