276 



THE AMERICAN NATURALIST 



[Vol. XLIV 



of these parts in the recent reptilia. I throw upon the 

 screen for purposes of easy comparison views of the ribs 

 as they are arranged in recent crawling reptiles and of 

 the ribs as they exist in the sauropoda, and more par- 

 ticularly in Diplodocas (Fig. 17). A glance at this dia- 



11st he sufficient to six 



he enormous dif- 

 ferences which exist, and to reveal to one who has the 

 least mechanical aptitude that the body, or 1 'barrel," of 

 the Diplodocus was constructed upon an ornithic rather 

 than upon a lacertilian model. The articulation of the 

 ribs does not lend itself to the idea that the animal pro- 

 gressed upon its belly. 



Professor Tornier says that the long tail of the sauro- 

 pod dinosaurs was intended to be carried at full length 

 upon the ground, to stiffen and guide the movement of 

 the anterior portion of the body. He speaks of it as 

 intended for anchoring the body, describing it as "ein 



