176 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, 
adult bird. The 2nd and 3rd have strong fused riblets, 4 millim. 
long, and the whole vertebra is 15 millim. across. Here is a sub- 
extinct type with three pairs of buttresses, or, in other words, three 
pairs of dorso-lumbar vertebree, covered by the pre-ilia; in Chauna 
there are eight such vertebree. 
The three next have only upper transverse processes (diapophyses) ; 
these, and those of the first three are all fused together above, and 
also to the ilia. Fenestree appear behind; there are four pairs of 
these between the upper transverse processes of the last five vertebree, 
all the rest of the roof is plastered over with thin bone—an ossified 
* aponeurosis.”” 
The 7th sacral has a small pair of inferior bars or riblets, in my 
older specimens, but these are not visible in the younger; but they 
make very little difference to the general concavity, right and left of 
the fused centra; the 7th vertebra is the lst urosacral. The 7th 
urosacral, or last general sacral, is the widest across its transverse 
processes, it is 30 millim. wide; the first of that series is only 13 
millim. across. The 9th, 10th, and 11th sacrals are carinate, below, 
the 12th and 13th recover their width, and these are not quite anky- 
losed together, even in the older specimen. 
The general concavity right and lett of the ankylosed centra, 
which is filled by the emerging nerves and the lobes of the kidneys, 
is not closed in behind, as in many birds, by rib-like thickness of 
the post-ilia, and special enlargement of the transverse processes of 
one or more of the urosacrals. 
Here we have the general open or unenclosed condition of the 
under surface, behind the “ pre-iliac buttresses,” that is seen in the 
Toucan aud the Woodpecker, a somewhat common state of things 
in birds with a rather short, broad, and gently convex pelvis, 
such as many of the Coccygomorphe possess. Unlike this state of 
things, we see in Corythaiz and Geocoecyx, as in the Raptores, a 
remarkable closing in of these concavities, by the special growth of 
post-ilia and the hinder urosacrals. 
Behind their middle, the series of the seven caudal vertebre (cd.v.) 
gradually shorten their transverse processes, which become wider as 
they shorten; the last free joint is 15 millim. across, the Ist is 29 
millim., a little less than the width of the last sacral. A rudi- 
mentary chevron bone is seen on the 4th, and a large growth 
of this kind is present on the 5th, 6th, and 7th. The latter or 
compound bone is 24 millim. long, slender, and subfalcate, being 
arched somewhat on its sharp dorsal edge. The ventral edge is 
thick, but sharpens out behind, where the bone is somewhat lobate, 
and from 2°5 millim. becomes 3 millim. across in front; this bone is 
7 millim. deep, it is evidently made up of 5 or 6 rudiments. 
Towards the end of the caudal series the procelous joint is 
established once more, and in the last of these articulations the joint- 
cavity is as complete as in the occipito-atlantal articulation ; this is 
a common character in arboreal birds with a large and very mobile 
tail. 
The sacral and caudal series both measure 48 millim. in length ; 
