COPE.] ' PALEONTOLOGY MIOCENE PERIOD. 515 



tion extends backward from each anterior zy gapophysis ; the neural 

 arch between them flat on the anterior half. 



Measurements. 

 Length of centrum below 0.0100 



Diameter of articular cnp,| reXar.;;;;;:::::;;::;:;::;::;;:::::;;::::; i1 



Diameter of base of diapophysis 0044 



Width between anterior zygapophyses 009S 



Width of upper plane pf neural arch .0078 



This species is as large as any of the existing species of Varanidce. 

 CEEMASTOSAURUS, Cope. 



Synopsis Vert. Colorado, 1873, p. 18. 



Established on vertebrse which differ from those of Feltosaurus in the 

 absence of the sharp ridges which connect the anterior zygapophyses 

 with the posterior in the dorsal vertebrse. They are better developed 

 in the cervical region. The species of this genus which are known are 

 ntermediate in size between those of Feltosaurus on the one hand and 

 Exostinus and Aciprion on the other. 



Dorsal vertebrae without zygosphene. 



The neural arch is capacious in the cervical region, and each neurapo- 

 physis is excavated below the posterior zygapopbysis, and sending a 

 ridge downward and backward round the centrum, continuing as a low 

 shoulder on the inferior face. Diapophysis with a single narrow capit- 

 ular articulation, extending obliquely downward and forward ; that of 

 the third vertebra smaller. Axis with an elevated neural arch, with 

 obtuse, inferior carina. Odontoid a crescentic element, with a transverse 

 groove on its anterior face. All the centra with an obtuse but promi- 

 nent hypapophysial keel. 



Cremastgsatjrtjs CARHsricoLLis, Cope, loc. cit, p. 18. 



Ball of sixth cervical vertebra round. Neural arches broad, each with 

 a low, acute keel for spine, which is elevated on the third, and produced 

 roof-shaped backward and forward on the axis. The costal articula- 

 tions are not produced below the centrum. 



^leasurements. 



M. 



Length of cervical vertebrse II to VI 0.0140 



Length of axis 00.38 



Elevation of axis behind 0047 



Diameter of odontoid, (in front) - 0034 



Length of c. VI 0029 



Diameter of ball of same 0011 



Total elevation of same 0030 



The dorsal vertebrae, which are appropriately associated with the cer- 

 vicals, have transversely-oval articular faces, and centra without infe- 

 rior keel or ridge. The vertebrse are all dorsal, hence the diapophyses 

 have the usual form in the order for costal articulation, and do not pro- 

 ject as far inferiorly as the i)lane of the lower face of the centrum. It 

 does not project beyond the anterior zygapophysis, and the lower half is 

 especially developed as the costal cond.vle. Neural spine a keel extending 

 from the front of the arch and rising into a short apex above the articu- 



