102 MEMOIRS OF THE CARNEGIE: MUSEUM 
of No. 878 are in the best state of preservation and are the elements from which 
the text figures have been drawn. Though not found in position (see P]. VII.) they 
are readily distinguished from the succeeding vertebree by their more modified 
centra and by their dorsal and transverse processes. 
Seen anteriorly (see fig. 9) the centrum of the atlas is pentagonal in form, wider 
Fic. 9. , Anterior view of atlas and axis of Baptunodon discus (No. 878). One half natural size. d., diapophy- 
sis; ., paired neural arch of atlas; s., spinous process of axis; z., apophysis with which the first intercentrum 
articulated. 
Fie. 10. Lateral view of atlas and axis of Baptanodon discus (No. 878). One half natural size. d., diapophysis of 
theatlas ; n., paired neural arch of atlas ; p., and p.’, parapophysis of the atlas and axis respectively ; s., spine of the 
axis ; z., apophysis of the atlas ; z.’, apophysis of the axis. 
than deep and considerably contracted inferiorly. The concavity for the reception 
of the occipital condyle instead of sloping from the outer margin to the center as in 
the centra that follow, has a narrow, flattened periphery, which is much enlarged 
laterally and inferiorly. The cup of the centrum descends evenly, perhaps more 
sharply, from the superior margin down to the center. The inferior surface presents 
a slightly rounded subtriangular face which looks downward and forward, its 
inferior extent reaching nearly to the middle of the coalesced centra. If present it 
was with this face or apophysis that the first hypophysis or intercentrum articulated. 
The superior lateral surfaces are quite extensive and curve backward to form the 
“para- and diapophyses. The dorsal surface is about equally divided between the 
