SHUFELDT : OSTEOLOGY OF THE STEGANOPODES 157 



So in the articulation of the eighth vertebra witli the ninth, a decided angle is 

 made — nearly a right angle — with its salient point to the front. This also occurs 

 between the ninth and the tenth and so on down the chain, becoming, however, less 

 and less marked, disappearing entirely after the fifteenth, after which the vertebrae 

 articulate in a straight line. The extremities of the long parapophysial processes of 

 the eighth vertebrae articulate in the shallow grooves on the forepart of the ninth 

 vertebra, on its ventral aspect. 



Garrod has said that ''Donitz figures a pair of accessory bony bridges on the 

 dorsal surface of the vertebra following the most lengthy one, which must evidently, 

 therefore, be the ninth. He, however, speaks of it as the eighth, which seems to me 

 to be an error depending on the omission of the consideration of the atlas, because 

 in Plotus anhinga (both from Brandt's figure and my specimens) it is most certainly 

 the ninth, as it is in Plotus novx-hollandix, Phalacrocorax carbo, and P. higubris. I 

 have, however, not seen Plotus levaillantii." 



"Donitz attributed the peculiar kink of the neck of the Darters, which it is 

 impossible to obliterate without lacerating the surrounding muscles, to the presence 

 of the bony bridges he describes; in this, however, he is mistaken, it depending on 

 the above-mentioned peculiarity in the eighth cervical vertebra, by which it is angu- 

 larly articulated with the seventh and ninth vertebrae, the upper genu being posterior, 

 and the lower anterior. In further verification of this, it may be stated that in 

 P. anhinga the bony bridges do not exist, and yet the kinking is most strongly 

 marked." (Coll. Scientif. Mem., pp. 336, 337.) The bridges here spoken of are also 

 absent in my specimen of A. anhinga. 



The neural tube is not very large in the first eight cervicals, where it has more 

 or less a cylindrical form posteriorly, but becomes somewhat antero-posteriorly com- 

 pressed as we gradually pass towards the fore end of the vertebra. Increasing again 

 in size after the ninth, it seems to attain its greatest capacity in the sixteenth, seven- 

 teenth and eighteenth, to become small and cylindrical once more as it passes through 

 the dorsal series. In the ninth and tenth vertebrte the anterior opening of the neural 

 canal lies in a plane which is about perpendicular, in each case, to the plane in which 

 the posterior opening is found. That is, upon direct dorsal view of either of these 

 two vertebrae, the posterior opening of the neural canal is not in sight, while we look 

 almost directly into the anterior opening. 



On the sixteenth vertebra we find the first pair of cervical ribs ; they are long 

 and slender and without uniform processes. We find also a large pair of free ribs 

 on the seventeenth cervical vertebra, which commonly have unciform appendages. 

 These are anchylosed to the bone, and .are large and broad. Next to these two pairs 



