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 vertebrae, covered by the pre-ilia ; in Ghauna 

 there are eight such vertebrae. 



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 vertebrse, 

 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 1st 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 

 miUim. across. The 9th, 10th, and llth 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 Coccygomorphae possess. Unlike this state of 

 things, we see in Corythaix and Geococcyx, as in the Raptores, a 

 remarkable closing in of these concavities, by the special growth of 

 post-ilia and the hinder urosacrals. 



Behii>d their middle, the series of the seven caudal vertebrae (cd.v.) 

 gradually shorten their transverse processes, which become wider as 

 they shorten; the last free joint is 15 millim. across, the 1st 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 procoelous 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 ; 



