100 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



the postzygapophyses of the preceding vertebra, as shown in the drawing of the 

 skeleton (plate 30). The postzygapophyses slightly overhang the centrum in the 

 distal caudal region. Most of the caudals have well-defined oblique chevron facets, 

 as shown in figure 1, plate 22. These become less and less well defined as the distal 

 end of the tail is approached. 



The tall neural spines and long slender chevrons of the anterior half of the 

 series would indicate a high thin tail for this part, but it becomes more and more 

 cylindrical toward the end. The whole apparently indicates, in life, a tail capable 

 of great transverse flexibility for the proximal portion, with a more sinuous move- 

 ment possible for the distal half. 



1 Chevron placed. 



= Vertebra restored. 



CHEVRONS. 



» Vertebra placed. 



The chevron bones present in the type are the second to the ninth, and the distal 

 series of 12 from the twenty-ninth to the fortieth. AQ were foimd articulated 

 excepting the fifteenth, which was placed as shown in plate 30. It was found 

 detached, but m a block of sandstone containing other bones of the skeleton, and 

 on the basis of this association was considered as belongmg to the type. The 

 anterior cheATons have suffered loss of parts siace the drawing was made for Marsh, 

 as may be seen at once by comparing figure 1, plate 22, with upper figure, plate 27. 



