262 MEMOIRS OF THE CARNEGIE MUSEUM. 
The Third Cervical Vertebra. 
The third cervical vertebra of specimen 1604 is well preserved. Six other 
third cervicals were recovered in a more or less imperfect condition. 
The prezygapophyses, which look inward and upward, are slightly convex 
upon their faces. The postzygapophyses, which look downward and outward, 
are very slightly concave transversely and convexo-concave from above downward, 
the concave portion of the surface being a narrow depressed transverse groove 
situated at the lower margin of the articular face, below which the outer surface 
Fig. 29. Lateral view of third cervical of M. elatus Fie. 30. Outline view of inferior surface of third 
(No. 1604). Xz. cervical of M. elatus (No. 1604). Dotted line 
shows point of section shown in Fig. 32. x3. 
of the bone forms a slightly raised marginal rim. The neural canal is large. The 
dorsal spine is well developed and greatly enlarged at its extremity by bulbous 
outgrowths on either side, which are, however, not so large and heavy as on the 
spine of the axis. The anterior articular surface of the centrum is hemispherical 
and looks downward, fitting thus into the corresponding articular surface of the 
axis, which, as has been already pointed out, projects strongly backward. The 
structure of the centrum corresponds to that of the atlas. The lower wall of the 
neural canal is quite thin, supported below by a high thin keel, which, arising 
immediately behind the anterior articulating surface of the centrum, gradually 
widens and thickens posteriorly until it melts into the posterior margins of the 
cup-shaped posterior articulating face, at its termination on both sides giving 
rise to two tubercular prominences. 
The transverse processes, which are very strongly developed, are formed as 
in the atlas by the union of upper and lower laminze between which at their origin 
