424 



0. C. Marsh — rJVew Cretaceous Dinosaurs. 



The astragalus was closely applied to the end of the tibia, 

 but not coossified with it. The fibula is strong and complete, 

 with both ends nearly equal in size. There were three functional 

 digits in the pes, with their metatarsals moderately elongate. 

 The terminal phalanges are broad, and ungulate in form. 



The ilium is intermediate in form between that of Iladro- 

 saurus and Stegosaurus, and its general characters are shown 

 in the cut below. The portion in front of the acetabulum is 

 very slender, and elongate. The face for the pubis is much 

 smaller than that for the ischium. 



Ilium of Claosaurus agilis, Marsh; side view; one-sixth natural size. 

 a, acetabulum ; is, surface for ischium ; p, surface for pubis. 



The present genus is very distinct from Nodosaurus, which 

 was described by the writer from a higher horizon of the 

 Cretaceous. The present animal had apparently no dermal 

 armor, and was of much more slender proportions. When 

 alive, it was probably not more than fifteen feet in length. 



The American Cretaceous Dinosaurs now known represent 

 several well-marked families, which may be arranged as follows : 



Order Theropoda. Carnivorous. 



(1) The Dryptosauridw, including the large carnivorous 

 forms, of which only imperfect specimens have been found, 

 but sufficient to indicate that they are distinct from the 

 Megalosauridce of the European Jurassic. Limb bones hollow. 

 Fore limbs very small. Feet digitigrade, with prehensile 

 claws. 



Order Ornithopoda. Herbivorous. 



(2) The Traokodontidos, herbivorous forms of large size, 

 with teeth of the Hadrosaurus type, in many rows. Cervical 

 vertebrae opisthoccelian. Limb bones hollow. Fore limbs small. 

 Feet digitigrade. 



