266 TOWARDS THE HUMAN FORM 



France, England, South Africa, and India have five digits to 

 each limb. The Megalosauria which flourished from the Trias 

 to the Upper Cretaceous in France, England, Colorado, and 

 India are slightly larger and have only four toes on their 

 hind feet. Hallopus victor of Colorado did not exceed one metre 

 in length ; its extremely short front limbs had only four digits, 

 its hind limbs three, the first being absent and the fifth repre- 

 sented by a short metatarsal. Ceratosaurus of the same region, 

 which exceeded five metres in length and bore a horn on its 

 nose, also had but three toes on its hind legs, but all three 

 metatarsals were united — a condition we shall see produced later 

 on in leaping and swift-footed animals. The Allosaurians of 

 North America possessed but three digits on all their feet. Finally 

 the hind legs of the small Compsognathus longipes of the Jurassic 

 of Bavaria were veritable bird legs whose three existing 

 metatarsals were united not only to each other, but also to 

 the distal series of the bones of the tarsus ; the proximal 

 series being likewise adherent, without being united to the 

 tibia, to which was joined a rudimentary fibula. In spite of 

 this the pelvis remained typically reptilian, and had behind it 

 a long tail. Sharply pointed teeth extended the whole length 

 of the jaws. Many Theropods (Ccehtrus, Hallopus, etc.) had 

 hollow bones presenting holes in their surfaces into which air 

 sacs dependent from the lungs were inserted, as with the birds, 

 from which these creatures were still far removed by the form 

 of their pelvis. 



The pelvis of the Orthopods, on the contrary, approximated 

 sufficiently closely to that of the Birds for Huxley to propose 

 for them the name of Ornithoscelidse. This form of pelvis does 

 not necessarily correspond to a permanently erect attitude ; 

 it implies no more than a great development of the posterior 

 members relatively to the fore-limbs, and the possibility of 

 erecting the body on them. The Reptiles grouped together in 

 the sub-order of Stegosaurians were still almost plantigrade. 

 Those of the genus Scelidosaurus, however, have only four digits 

 on each foot, while in Stegosaurians there remain but three 

 on the posterior feet. The Scelidosaurians slightly exceeded 

 four metres in length ; they lived at the time of the Lower 

 Jurassic (Lias) of Lyme Regis. Analogous forms are also found 

 in the English Wealden (Hylceosaurus poly acanthus). The 

 Stegosaurians of the Upper Jurassic of Wyoming and Colorado 



