174 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, 



small spine that looks forwards ; this structure is seen, but not so 

 well, in the 6th and 7th, and then dies out. 



The 6th is the longest of the series ; it is 13-3 miUim. long, and 1 1 

 miUim. wide, over the pre-zygapophysis. The 9th and 10th have 

 oval knobs on their post-zygapophyses. The upper spine begins 

 ao-ain on the 12th, on the 14th it is oblong and large Hke those of 

 the dorsals, but smaller; in the loth it is three fourths the size of 

 those on the dorsals. The last six cervicals have a small inferior 

 spine ; this is trifid in the 14th, and is dilated into a broad plate in 

 the last. The 13th has a small, free, V-shaped rib ; in the 14th 

 the left rib is very slender, but it is 22 miUim. long, whilst its right 

 rib is" only 7 millim. long. On the right side the 12th has a V" 

 shaped, distinct rib. The last cervical only differs from a dorsal in 

 having no sternal piece ; it has the uncinate process or bone (this 

 is a distinct element), and is nearly as long in the 1st dorsal. The 

 posterior part of this 1 5th vertebra is intermediate in character 

 between cylindroidal and opisthoccelous. My memory fails me in 

 endeavouring to think of any other existing bird with more than 

 three distinct ribs in the cervical region, even on one side ; there is 

 often a want of symmetry in this part of the spine, as well as in 

 other parts, e.g., atlas, sacrals, &c. This fact — that, at least on 

 one side, four ribs remain free in the lower part of the neck — 

 coupled with what I shall now show as to the structure of the dorsal 

 vertebrEe, gives me the right to say that this is a very archaic or 

 quasi-reptilian type. 



The four dorsal vertebrae have very long and sharp upper spines, 

 and the first two have, also, simple lower spines ; the dilated plate 

 seen in the last cervical has died out, and the process itself greatly 

 elongated, downwards. The front face of the 1st dorsal centrum is 

 cylindroidal, the rest of the articulations of the dorsals and the last 

 dorsal with the 1st sacral is opisthoccelous. The centra are narrow, 

 alm.ost Chelonian in this respect, the 1st and 2nd are 7nere keels. 



The posterior cup of each dorsal centrum is well excavated, and 

 there is, right and left, at its upper part, a pair of semi-oval enlarge- 

 ments of this facet, that look like an additional pair ofzyrjapophyses ; 

 hence, on the side view, the outline of the hollow end of each cen- 

 trum is deeply notched at its upper third. Each of these secondary 

 facets has its own concavity, so that each centrum fits to the one 

 behind it by three hollow facets, one large, below, and two small, 

 above ; the articular cartilage is very thick in these vertebrae. Thus, 

 although this mode of articulation is archaic, it is also intensely 

 specialized by this modification (Plate XVIII. figs. 5, 6). 



Up to the present, this is the only Cuculiue type, except the Psit- 

 tacida, in which I have found the dorsals to be opisthoccelous. It is 

 common among Water ' and Wading birds. 



The ribs (Plate XIX. fig. 1) are very peculiar; they resemble 

 those of the Hornbills, but the peculiarity seen in those birds is 

 exaggerated in this. This is worth considering, as we have just 



^ The secondary facets just described are uot so distinct in Parrots and 

 Plovers as in Steatomis, which is equal to Chionis in this respect. 



