18 P. S. Lull — Dinosaur ian Distribution. 



with the persistently primitive Weal den Ilypsilophodon, v. 

 Huene derives from the Colorado jVanosaurus. Lull (1910) 

 will report Dryosaurus also from the basal Potomac beds 

 of Maryland, and Gilmore (1909, pp. 392-395) has described 

 a Camptosaums from the Lakota in South Dakota. 



The Wealden of England and especially of Belgium has 

 yielded remarkably preserved specimens of Iguanodon, the 

 successor of Camptosaurus. lyuanodon is in turn succeeded 

 in the Cenomanian of England by a type referred to the. Ameri- 

 can genus Trachodon, but somewhat questionably. 



In America, the Niobrara, the equivalent of the European 

 Turonian, has yielded the type of Claosaurus agilis, which is 

 followed in the New Jersey Greensand and in probably 

 equivalent beds of North Carolina by Trachodon (Hadro- 

 saurus). 



In the West, Trachodon is found in the Judith River beds 

 and again in the Laramie, where it lingers on until the final 

 extinction of the dinosaurian race at the close of the Mesozoic. 



The European Cenomanian has produced Craspedodon m 

 Belgium and Mochlodon from the Gosau formations of Aus- 

 tria. Phabdodon, found in Rognac of southern France and 

 in the Msestricht beds of Belgium and Holland, both of the 

 Danian period, is probably the closing member of the race in 

 Europe. 



Armored Orthopoda — Stegosauria. 



The Stegosaurs have their first known representative in 

 Scelidosatorus of the English Lias, beyond which the record is 

 blank until we come to Dacentrus (Omosaurus) of the Kimme- 

 ridgian, which appears to be the central type in the evolution of 

 this group. The Morrison yields Stegosaurus, which some 

 authors have identified with the European Dacentrus, but 

 which appears to be an aberrant side branch derived also from 

 the Scelidosaurian stem. In the basal Potomac beds of Mary- 

 land several teeth and more questionably a vertebrum (Lull 

 1910) are described as Priconodon and referred to the 

 Stegosauria. 



The Purbeckian of England has also yielded Priconodon, 

 while from the Wealden come Polacanthus and Hycelosaurus, 

 the latter being found in Belgium as well as in England. 

 Acanthopholis, from the English Cenomanian, v. Huene makes 

 the connecting link with Ankylosaurus of the Laramie. 



Intervening forms in the series, however, are probably repre- 

 sented by Nodosaurus f rom the Pierre (Turonian) of Colorado, 

 while Stegopelta, recently described by Williston (1905, pp. 

 503-505) from the Lower Benton of Wyoming, and Palceo- 

 scincus of the Judith River are closely related if not identical 



