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 millim. long, and 11 
millim. wide, over the pre-zygapophysis. The 9th and 10th have 
oval knobs on their post-zygapophyses. The upper spine begins 
again on the 12th, on the 14th it is oblong and large like those of 
the dorsals, but smaller; in the 15th 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, Y-shaped rib; in the 14th 
the left rib is very slender, but it is 22 millim. long, whilst its right 
rib is only 7 millim. long. On the right side the 12th has a Y- 
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 Ist dorsal. The 
posterior part of this 15th 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, &e. 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 vertebree 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 Ist dorsal centrum is 
eylindroidal, the rest of the articulations of the dorsals and the last 
dorsal with the Ist sacral is opisthocelous. ‘The centra are narrow, 
almost Chelonian in this respect, the Ist and 2nd are mere 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 of zygapophyses ; 
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 vertebree. 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 Cuculine type, ewcept the Psit- 
tacide, 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 
1 The secondary facets just described are not so distinct in Parrots and 
Plovers as in Steatornés, which is equal to Chionis in this respect. 
