THE UPPEE TRIASSIC OP WESTERN TEXAS. 



81 



posteriorly the lower face becomes rounded from side to side, with no trace of a keel 

 or lateral ridges or angles. The posterior portion of the centrum descends slightly, 

 maintaining its rounded outline. The posterior face has an oval outline, being higher 

 than wide, due to the development of a lip on the lower edge. It is concave, but less 

 so than the anterior face, and slants from above downward and backward. Length 

 of the base of the centrum, 52 mm. 



The second of the series (seventh (?) cervical) is much more complete. It lacks 

 the anterior zygapophyses and the neural spine. In this vertebra the anterior face is 

 complete; it is deeply concave and is inclined parallel to the posterior face of the preceding 

 vertebra, i. e., from above downward and backward. "On either side of the anterior 

 portion of the centrum there are two processes; the upper begins as a low ridge at 

 about the middle point of 

 the side of the centrum id 9c, 



and extends forward to the 

 edge of the anterior face, 

 becoming more prominent 

 during its advance. The 

 second process, below the 

 first, is shorter, not over 

 12 mm., and heavier; it 

 continues out upon the 

 edges of the anterior face 

 of the centrum, forming a 

 narrow triangular face 

 which looks downward 

 and outward and slightly 

 forward. These two pro- Fig. 31. 



cesses are distinct, as q^^.^-^^^^ and dorsal vertebra of a small Dinosaur, Coelophysis, sp. No. 7507, 



shown by several vertebrae, U. of Mich, x 0.5. 



but are very suggestive of j tt • 



the complete arch figure by Marsh^ in Coelurus and described by Cope and Huene m 

 Coelophysis longicollis. It is possible, even probable, that there was such a complete arch 

 in the anterior cervicals, but in the posterior portion of the cervical series the arch has 

 broken into distinct diapophysis and parapophysis. The posterior zygapophyses are 

 depressed and elongate, extending back nearly as far as the upper edge of the posterior 

 face of the centrum. The rest of the vertebra is much like the preceding one. Length 

 of the base of the centrum, 52 mm. 



The third of the series (eighth (?) cervical) has the upper process on the side ot the 

 centrum stronger and extending outward more than in the second; the process is a little 

 higher on the side of the centrum. The lower process is shorter and has a larger face 

 The anterior zygapophyses are preserved; they are horizontal, heavy, and extend well 

 forward of the anterior face of the centrum. Length of the base of the centrum, 44 mm. 



The fourth of the series (ninth (?) cervical) has the anterior zygapophyses locked 

 with the posterior ones of the third; they are still nearly horizontal, but are slightly inchned 

 upward. The upper process on the side of the centrum is now very strong and stands 

 well out from the vertebra; it is so high upon the centrum that its lower edge is but 

 slightly below the lower face of the neural canal. The anterior edge of the centrum 

 is injured, but it can be seen that the lower process is now but a triangular face on the 

 lower edge of the face. Length of the base of the centrum, 42 mm. 



Geological Survey, plate vii, 



1 Marsh, O. C, Dinosaurs of North America, Sixteenth Annual Report U. S. 

 figs. 2, 2a, 1896. 



