194 MEMOIRS OF THE CARNEGIE MUSEUM 



Not especially stout, the lateral pedicels support a broad, oblong neural arch, 

 which has a straight anterior, and a concave posterior margin. Air gains access to 

 this vertebra through some holes situated in or near a small concavity, over which 

 articulates the ventral surface of the odontoid process of the axis when the bones 

 are in situ. A polishing of the surface alone indicates the points where the ante- 

 rior margin of the neural arch comes in contact with the occipital bone of the 

 cranium, and where the ventral aspect of its posterior margin rides on the upper 

 part of the anterior margin of the neural canal of the axis. 



A broad-based, swollen, and tuberous neural spine is one of the chief characters 

 of the last-named vertebra, while its bpemal spine, situated posteriorly on the centrum, 

 is transversely compressed, sharp along its infero-mesial border, and withal rather 

 inconspicuous. 



The articular surface on the body for the atlas is deeply concave, and always 

 presents a large mesial pneumatic foramen at its base, just beneath the odontoid 

 process. Posteriorly, the neural arch of this vertebra far overhangs the centrum 

 below, while either postzygapophysial portion of it, not strictly defined from the 

 bone, has upon its direct ventral aspect a large oval articular facet for articulation 

 with the corresponding ones at the prezygapophyses of the third vertebra. 



We have no lateral canals in the axis vertebra of this Pelican, but a small pneu- 

 matic foramen is usually seen on either side, at the site of their occurrence in the 

 next bone of the spine behind it, at points where they open posteriorly. In the 

 third, fourth, fifth and sixth vertebra the neural spine is represented by a low, 

 lengthy, and thickened ridge, which fails in any case to reach the dorsal margins of 

 the neural canal, either in front or behind. In the seventh vertebra the neural 

 spine is much restricted, occupying only the center of the bone. It begins to dis- 

 appear in the eighth ; is almost absent in the ninth and tenth ; feebly reappears in 

 the eleventh and twelth ; begins to be tuberous in the thirteenth ; and from this 

 on it slowly assumes the form it has in the dorsal series, where it is low, thickened, 

 and wedge-shaped, with base behind and apex in front. 



Far back on the centrum of the third vertebra we find a short, thick, and low 

 heemal process ; somewhat resembling the one on the axis. The character is quite 

 obliterated in the fourth vertebra, where we begin to see, anteriorly beneath the 

 extreme fore part of the centrum, the first indications of the formation of the carotid 

 passage. They are more distinct in the fifth vertebra ; still more so in the sixth ; 

 decidedly so in the seventh, where the remarkable peculiarity exists in that a carotid 

 channel with thin, conspicuous side-walls abruptly develops at the extreme hinder 

 end of the centrum. This character is just as well marked in the eighth vertebra, 



