516 GEOLOGICAL SURVEY OF THE TEEEITORIES. 



lar ball. There is a collar round the ball, which is faintly visible on the 

 inferior side. 



Measurements. 



M. 



Length of centrum 0.0040 



Width of cup ; 0018 



Depth of cup 0010 



Elevation of neural arch anteriorly 0015 



Elevation of neural spine and arch posteriorly 0043 



Total expanse in front 0047 



The dorsals represent several individuals. 



Ceemastosaurus unipedalis, Copej Diacium unvpedale, Cope, Syn- 

 op. Vert. Col., p. 18. 



Represented by a sacral vertebra of an individual smaller than any of 

 those of the last-described species, and characterized by the unusual 

 protuberance of the articular ball and absence of flattening of the cen- 

 trum below. Centrum depressed ; plane longitudinally convex in trans- 

 verse section. An* annular groove round the ball. Diapophysis elon- 

 gate, slightly depressed. 



Measurements. 



M. 



Length of centrum 0.0034 



•Diameterofcup,|^^;;;";;;:;:;:;;;:";:;:;:::::;;:;::;:::;;":;; ^ 



PLATYRHACHIS, Cope. 



Synopsis Vert, Colorado, p. 19. 



Char. gen. — Dorsal vertebrae united by the zygosphene, as well as the 

 usual articulation. Centrum Diuch depressed, flat below. Neural arch 

 depressed, an angle connecting the zygapophyses. Neural spine a keel, 

 projecting beyond the posterior margin in a mucro. 



PLATYRHACHIS COLORADOENSIS, Cope, loc. cit, p. 19. 



Char, specif. — Ball truncate below its convex face, looking slightly 

 upward. Costal capitular surface semiglobular directly below the an- 

 terior zygapophysis. Neural arch concave between zygapophyses. 



Measurements. 



M. 



Length of three dorsal vertebrae - 0.0070 



Length of one dorsal vertebra 0028 



transverse 0014 



Diameter of ball, ^^^j.^.^^^ _ ^^^^ 



Elevation of vertebra 0019 



Width between zygapophysis - .0025 



The size of this species is similar to that of the two species already 

 described from teeth ; bat the vertebral articulation is not appropriate 

 to Exostinus with existing lights. 



OPHIDIA. 



NEUEODEOMICUS, Cope. 



Synopsis Vert. Cblorado, p. 15. 



Gliar. gen. — Centrum small, with a prominent truncate hypapophysis. 

 Neural arch capacious, the zygantrum wider than the articular cup. 

 Neurapophyses bounding the canal laterally below the zygosphene; its 



