5i6 HISTORY OF THE DINOSAURIA. 



Zanclodon, distinguished by having only two vertebrae in the sacrum. 

 The Lias has j'ielded the well-armoured genus Scelit/osaurus, and some 

 undescribed forms. Megalosaurns, though best known from the 

 Stonesfield slate and Wealdeii beds, appears from teeth to date back 

 to the Lias, and survive to the Gosau beds, which are of the age of 

 the Upper Greensand. Cetiosaurus abounds in the Forest Marble, 

 Kimmeridge Clay, and Wealden beds. Cryptosaurus is found with 

 Megalosaurus in the Oxford Clay. Priodontognathus probably belongs 

 to the Calcareous grit. Kimmeridge Clay genera include Omosaurus 

 and Gigantosaurus. The Wealden beds are characterised by lyuanodon, 1 

 perfectly preserved in Belgium, which ranges down to the Kimmeridge 

 Clay, and perhaps upward to the Upper Greensand. With it occur 

 Hylceosaurus, Hypsilosphodon^ Pelorosaurus, Vectisaurtts, Polacanthus, 

 and Ornithopsis. Craterosaurus is found in the Neocomian Sands. 

 The Upper Greensand of Cambridge includes such genera as Acantho- 

 polis, Macrurosaurus, Anoplosaurus. Syngonosaurus,&n<\. Eucercosaurus? 

 The Gosau fauna includes 4 the genera Mochlodon Struthiosaurus, 

 Cratceomus, Ornithomerus, Doratodon Rhadinosaurus, Oligosaurus, and 

 Hoplosaurus. Pleuropeltus may possibly prove to be another Dinosaur 

 allied to Polacanthus. The most recent dinosaurs found in Europe are 

 from the Maestricht beds. They are referred to the genera Orthomerus 

 and Megalosaurus. 



The American Dinosauria are numerous. Their exact age is uncer- 

 tain. Some are Cretaceous ; others are regarded as Jurassic. Professor 

 Marsh has greatly subdivided the group, 5 as in the following provisional 

 classification : 6 



SUB-CLASS DINOSAUKIA. 

 I. Order SAUROPODA. 



Family Atlantosauridse : Atlantosaurits, Apatosaurus, Bronto- 



saurus, Camarasaurus, Dystrophceus. 

 Family Diplodocidas : Diplodocus. 

 Family Morosauridae : Morosaurus, Cttiosaurus, Oniithopsis, 



Emamerotus. 



II. Order STEGOSAURIA. 



Family Stegosauridae : Stegosaurus, Diracodon Omosaurus. 

 Family Scelidosauridae : Scelidosaurus, Acanthopholis, Cratceomits, 

 ffylceosaurus, Polacant/tus. 



III. Order ORNITHOPODA. 



Family Camptonotidae : Camptonotus, Laosaurus, Nanosaurus^ 

 Hypsiiopkodon. 



1 Dollo, Bulletin du Mus^e Royal d'Histoire Nat. de Belgique. 



2 Hulke, Phil. Trans. Royal Soc., Part III., 1882; loc. cit., Part III.. 1881 ; 

 and numerous papers in Q. J. G. S. 



3 Q. J. G. Soc., vol. xxxv. 4 Quart. Jour. Geol. Soc., vol. xxxvii. 



5 See Marsh, in American Journal of Science, vols. xiv.-xxvii. Cope, United 

 States Geol. Survey of the Territories, vol. ii. 1875, &c. 



6 American Journal of Science, vol. xxiii., January 1882. 



