100 University of California. [vol. 3 



bluff near the Cove, three miles from Madison's Ranch, on 

 Squaw Creek. The horizon at which they occurred seemed to be 

 near the base of the Atractites beds. The bones all appear to 

 belong to one individual. They include five vertebrae from the 

 posterior and middle dorsal regions, several well preserved ribs, 

 one complete limb bone, a fragment of another, and a piece of a 

 large arch bone. 



On four of the vertebrae the summits of the diapophyses are 

 below and disconnected from the upper surface of the centrum, 

 while the lower ends are relatively near the inferior surface (PI. 15, 

 fig.l). The diapophysial ridges on these individuals are long, 

 slender, and much constricted at the point where the lower part 

 swings forward. As is shown in the table of measurements follow- 

 ing, the height of the centrum is slightly greater than the width. 

 The greatest breadth is considerably below the middle, which 

 gives the centrum a pear-shaped cross-section. 



Measurements of a centrum on which the diapophyses do not 



reach the summit. 



Height 97 mm. 



Greatest width 92 



Length 46 



Height of diapophysial ridge 62 



Width of diapophysis at constriction 9 



Greatest width of lower extremity of diapophysis 21 



Height of upper arches with these centra 120 



Antero- posterior diameter of spines at widest point 



above posterior zygapophyses 34-32 



Transverse diameter at the point where antero -posterior 



was taken 27-27 



The other vertebra (fig. 2) has a length of 41 mm. and is 

 consequently somewhat smaller than the four already discussed. 

 Its diapophysial ridge reaches the summit of the centrum, and the 

 articular surface is confluent with that for the reception of the 

 upper arch. This centrum belongs apparently to a middle dorsal 

 and the other four followed close behind, probably separated 

 from it by only a few individuals. 



One of the distinguishing characters of this species is found 

 in the form of the upper arches, which are remarkably high 

 and thick (figs. 3 and 4). The margins of the spines 

 are very thin, particularly on the lower portion of the anterior 



