OPHIDIA. 783 



Ogmophis oregonensis Cope. 



PlateLVIIIa; figs. 9-11. 



This snake is represented by four dorsal vertebrae and probably by a 

 fifth from the region near the skull. The last-named vertebra has a smaller 

 centrum than the others, as is usual with those from the anterior part of the 

 column, but the details of its structure are much as in the others. It has 

 an acute hypapophysial ridge which extends posteriorly into a short, sub- 

 acute process. In the other centra, the median inferior ridge bounded by 

 the lateral grooves, is obtuse, and has different forms. It is wide at both 

 extremities and the surface is equally convex ; in two others it is much 

 narrowed medially and widened posteriorly. In all of these the posterior 

 part is slightly angulate medially. The articular faces are nearly round, 

 and the obliquity of the ball is only moderate. The ridge from the inferior 

 extremity of the rib surface terminates a short distance from the articular ball. 

 The ridge connecting the zygapophyses is very prominent. The rib articular 

 face is one-half deeper than wide; the superior half is convex, the remainder 

 gently concave, the inferior border projecting slightly outwards. 



The only specimen of this species preserved rather exceeds in size the 

 others here described, excepting the Neurodromicus dorsalis. 



Measurements. 



M. 



Length of centrum witb ball 0.0050 



Transvetse diameter of ball 0026 



Total elevation of vertebra 0060 



Elevation of neural spine 0019 



Width at interzgyapophj'sial ridge 0044 



Vertical diameter of rib surface 0023 



Width of ball of a " cervical" centrum 0020 



From the John Day beds near the John Day River, Oregon. J. L. 



Wortman. 



Ogmophis angulatus Cope. 



Calamagraa angulatus Cope. New Vertebrata Tertiary of Colorado, 1875, p. 16. Annual Report U. S 



Geol. Surv. Terrs., 1873 (1874), p. 518. 



PlateLVIIIa; fig. 12. 



This species differs from the C. oregonensis in the following points. The 

 interzygapophysial ridge is not nearly so prominent but is excavated behind 

 the prezygapophysis. The neural spine is smaller and is not split poste- 



