470 THE WASATCH FAUNA, 



The axis is of moderate elongation, and has a very oblique, slightly 

 concave, posterior articular face. Its form is that of a deep semicircle, 

 with a truncate protuberance below. The spine is produced obliquely 

 upwards and backwai-ds, and is low in front. The postzygapophyses are 

 large. The diaparapophyses unite into a short, acuminate backwards 

 directed process, which extends to below the middle of the postzygapophy- 

 ses. 'J'he atlantal facets are well turned upwards, and are hence deeper 

 than wide. The odontoid process is cylindric, and its inferior articular 

 surface is distinct from that of the atlantal surfaces. The inferior keel of 

 the centrum is weak in front, but projects behind into the j^rotuberance 

 already described. 



In four succeeding cervicals the articular faces of the centra are sub- 

 round. In the third, fourth, and fifth the transverse process extends but 

 little posterior to the posterior articular face, and the inferior edge does not 

 descend to the level of the hypapophysial edge. On the sixth vertebra the 

 diapophysial portion is directed u^jwards from the vertebrarterial canal, 

 while the parapophysial portion extends almost vertically downwards, so 

 that its horizontal inferior edge falls considerably below the hypapophysial 

 line. On this vertebra also the neural spine first assumes important dimen- 

 sions. The seventh cervical is mostly concealed by matrix. The zyga- 

 pophyses in all the cervicals posterior to the axis are connected by a 

 prominent but very obtuse ridge, and the roof of the postzygapophysis is 

 thickened. The neural arches are quite flat on top. 



The modifications seen in the forms of the dorsal vertebra, as we trace 

 them from before backwards, are the following: In the first vertebra the 

 anterior articular is a little wider than deep; the relative width increases 

 until on the posterior centra it much exceeds the depth. The usual change 

 in the prezygapophyses is seen. On the first they are like those of the 

 cervicals, horizontal and looking upwards and inwards; on the third they 

 have already become sessile convexities, looking upwards and forwards, and 

 it is not until the eleventh vertebra that they begin to resume the horizon- 

 tal up-looking character. On the first dorsal the diajoophysis is robust and 

 prominent, and has a large concave capitular facet. It is less prominent on 

 the sixth, and has a subround extremity, and on the ninth it is surmounted 



