ORDER DINOSAURIA. 



II63 



neural canal in the sacrum. In the solid structure and general 

 contour of the limb-bones, as well as in the relations of the 

 sacral centra to their arches, Stegosaurus approximates to the sub- 

 order Sauropoda ; and thus shows how impossible it is to bring out 

 the true relationships of animals in a linear classification. The 

 type species indicates a reptile about two-thirds the dimensions of 

 Iguanodon bernissarte?isis. The American species have no inner 

 trochanter to the femur. The 

 name Diracodon has been ap- 

 plied to an American Jurassic 

 type characterised by some modi- 

 fication in the structure of the 

 foot. Dystrophceus, from the 

 Trias of Arizona, appears to be 

 more or less closely allied to the 

 Stegosanrida. 



Family Ceratopid^e. — This 

 name has been proposed for 

 some remarkable Cretaceous 

 Dinosaurs allied to the preced- 

 ing family, but can only be pro- 

 visionally adopted. The type 

 genus Ceratops (according to 

 Cope identical with his Poly- 

 onax), of the Laramie Creta- 

 ceous of the United States, 

 carries a pair of large horn-cores 

 on the skull, which are curiously 

 like those of the JBovidcB, and 

 were probably sheathed with 

 horn. The body was covered 

 with dermal scutes, which not 

 improbably had overlying horny 

 shields like those of Chelonians. 



In the Upper Greensand of Austria there occur similar horn-like 

 bones, once thought to have been attached to the body, and 

 described as Struthiosaurus (Cratceomus), and it has yet to be 

 shown that the American types are generically distinct. A gigantic 

 allied form, from the Laramie, has been christened Triceratofis, 

 and is characterised by the presence of an additional nasal horn- 

 core, supported by the coalesced premaxillse and an additional 

 rostral bone. The skull is stated to be upwards of six feet in 

 length ; the frontal horn-cores measuring some 2 2 inches. A 

 horn-core-like bone in the British Museum, from the Wealden, 

 not improbably indicates an allied type. 



pectoral and pelvic 

 girdles and limbs of Stegosaurus uugulatus ; 

 from the Upper Jurassic of North America. 

 £5 natural size, s, Scapula ; c, Coracoid ; /z, 

 Humerus ; r, Radius ; ti, Ulna ; i-v, Phalan- 

 geals ; il, Ilium ; is, Ischium ; /, p 1 . Pubis ; 

 f, Femur; t, Tibia; /*, Fibula; a, Astra- 

 galus ; c, Calcaneum. (After Marsh.) 



