\v. c. KNIGHT — JURASSIC ROCKS OF SOUTHEASTERN WYOMING 



characters. The American Ichthyosaurs, so far as known, are closely 

 allied to the European Opthalmosaurus,* which is Middle Jurassic, and 

 the great Magalneusaurus f is closely related to the English Pliosaurus, 

 which is Upper Jurassic. In view of these facts, no further suggestion 

 can be offered at this time. In this, as in other stages, harmony should 

 prevail in the evidence offered, and until the great difference can he re- 

 moved it must suffice to call the Shirley stage Jurassic, but remember- 

 ing that the bulk of evidence offered at the present time would not place 

 it higher than Middle Jurassic. 



* A. s. Woodward: "Vertebrate Paleontology," p. 18:;. 

 f Am. .lour. 8ei., vol. v. pp. 378-380. 



