OF COLYMBUS TORQUATUS. 141 



This aperture communicates directly with its fellow, and also with the palatal fissure, as 

 as well as with the nasal passages generally. 



Of the Vertebral Column. 



Cervical vertebrae. The cervical portion of the spinal column consists of thirteen vertebras. 

 These, as usual among Avcs, are very freely movable upon each other, not only antero- 

 posteriorly in the direction of the axis of the body, but the lateral movement is also 

 exceedingly free. Tbere does not appear, however, to be anything very peculiar in their 

 articulations with each other. The vertically concave and horizontally convex facet 

 upon the posterior extremity of one vertebra is received into the vertically convex and 

 horizontally concave anterior extremity of the next succeeding ; and the smooth flat facets 

 upon the oblicpue processes glide in the ordinary way upon each otber. The planes of 

 these articulations are so arranged as to produce, taken together, the ordinary *• sigmoid " 

 flexure of the neck of the bird. The feature of the extensive lateral motion of the 

 neck appears to be more strongly marked than is ordinarily the case among the Urinatores, 

 except perhaps the Podicipidce ; the long-necked genera of which, such as JEchmophorus, 

 etc., probably surpass it in this respect. This lateral motion is most extensive between the 

 lower cervical vertebrae. 



Although these vertebrae possess characters which most readily separate them from those 

 of any other portion of the column, they yet differ greatly from each other, in different 

 portions of the neck. Throwing out of consideration the atlas and axis, which of course 

 are quite unlike the others, we still find that scarcely any two vertebra? possess exactly 

 the same shape, size, and special characters. Beginning with the third vertebra, and pro- 

 ceeding backwards, we find that the length of the bodies increases successively to about 

 the eighth or ninth, when it again decreases rapidly, so that the last one is not so long as 

 the third. The body of the third is thin, being exceedingly compressed vertically; and 

 coincidently with the lengthening of each one successively to the eighth or ninth, they 

 grow wider, and comparatively not so deep vertically ; those that follow, however, do not 

 again grow more conrpressed as they shorten ; but on the contrary become broader and 

 broader, so that the last one is as wide as deep, and very stout and strong. With this 

 widening, there is also, towards the posterior extremity of this portion of the spine, a very 

 high development of the transverse processes of the anterior extremities of each vertebra. 

 This is so considerable, that the width across these transverse processes much exceeds the 

 length of the whole vertebra. These processes are also exceedingly stout, with several 

 roughened eminences for muscular attachments ; and the foramen for the vertebral artery, 

 which their two roots form, is as large as the spinal canal itself. Now as we proceed up 

 the neck to the head, these transverse processes project less and less from the bodies 

 of the vertebra), and become less robust and angular, at the same time that they are 

 antero-posteriorly elongated ; and possess regular lamelloid walls, so as to form rather 

 canals than simple foramina for the artery. 



The " styliform processes " or " rudimentary ribs " appear to arise from the posterior 

 aspects of the summits of each of the transverse processes, beginning with the third ver- 

 tebra. They are directed backwards, exactly parallel with the axis of the column, and, 

 according to their length, form a more or less complete osseous covering and protection to 

 the vertebral artery during its passage between any two contiguous foramina. These 



