Smui'KLdi' : OsTEOLO(.;v OF nil I'i.aminc.oks. 307 



formiiii; the paraj^ophysial canal for the carotid arteries. This canal 

 remains o|>en throughout the series, where it is always seen to be short 

 and situated at the extreme anterior jiart of the centrum beneath. It 

 is well marked in the last five or six vertebrce of the neck, and even 

 appears to be present on the 19th vertebra, or the first one of the 

 solid dorsal bone. Its place is taken by a single, forward-directed 

 spine on the 20th, and after that every trace of it disappears. The 

 lateral vertebral canals are also at the extreme anterior jiart of the 

 several cervical vertebras that ])Ossess them, and they, too, are very 

 short, being found first in the third cervical, and continue to be pres- 

 ent to embrace the seventeenth. After that free pleurapophyses are 

 in order. These vertebral canals are of very small calibre in the lead- 

 ing cervicals, but gradually become larger, until they are of some size 

 in the i6th, 17th and iSth vertebrx\ The parapophysial spines form 

 a \ery remarkable feature, they being of very considerable length, and 

 of absolutely hair-like dimensions. In the 15th vertebra the pair 

 suddenly shortens up, to become quite unnoticeable, and in the i6th 

 vertebra they are supplanted, upon either side, by a low inconspicuous 

 tubercle. The 15th vertebra is also peculiar in possessing interzyga- 

 pophysial bars, which are so often present in the third cervical of 

 other birds, but which in tlie present bird are almost aborted in that 

 segment of the spine. 



The zygapophysial processes are very short and thick in the first six 

 cervicals, leaving, when the \ertebrfe are articulated, no lozenge- 

 shaped interspace upon vertical view between the bones, but in the 

 seventh vertebra the posterior pair begin to elongate, and this is con- 

 tinuous to include the 14th, whereupon they again shorten and thicken 

 throughout the lower part of the neck and the back. When the ver- 

 tebras are normally articulated in the cervical region, the si)ine there 

 forms a long sigmoid curve down to the dorsum. As a rule the artic- 

 ular facet on the anterior part of the centrum is extremely shallow in 

 the vertical direction and correspondingly wide transversely ; the pos- 

 terior interarticular facet, on the other hand, has more or less of a 

 quadrilateral outline. All this holds true, especially in the leading 

 cervicals, whereas in the last free dorsal vertebra, both anterior and 

 posterior facets are strictly of a quadrilateral outline. They are 

 " heteroccelous" throughout the spine, with the exception of the atlas, 

 which is, of course, procoelous anteriorly, with its posterior face, 

 slightlv convex. 



