SHUEELDT.] OSTEOLOGY OF THE SPEOTYTO. 611 
The pleurapophyses and parapophyses are very rudimentary or en- 
tirely suppressed. Each vertebra bears a prominent neural spine, which, 
from the first to the sixth, inclusive, is bifurcated; in the last two it ap- 
pears aS a mere primitive knobule. The transverse processes are all 
deflected downwards and outwards, very small in the first and still more 
so in the last; are largest in the fifth and sixth. Prezygapophyses are 
well marked; they reach forwards and articulate with the feebly devel- 
oped postzygapophyses. In a few of the posterior segments there ap- 
pears to be an effort on the part of the neurapophyses to overlap the 
vertebra next beyond them. The neural canal is pervious throughout, 
commencing in the first with a calibre equal to that in the end of the 
sacrum; it gradually diminishes, and terminates in a minute, blind, con- 
ical socket in the pygostyle. Hypapophyses are produced downwards 
in a few of the ultimate vertebre. They hook forwards and articulate 
with the centrum of the vertebra next beyond them. Sometimes they 
are observed to be free, or rather resting upon a facette on the anterior 
Inargin of ome centrum and extending over to the anterior margin of the 
centrum of the vertebra anterior to it, to meet a similar facette, as a 
tiny styliform process. The spinal column is completed posteriorly by 
the pygostyle—that ploughshare-shaped segment that articulates with 
the last coccygeal vertebra. Above its cup-shaped facet this bone arises 
as a laterally compressed plate, extending backwards and bifurcated at 
its extremity, as if te imitate the neural spines of the vertebre of the 
series of which it is an ultimate appendage. Below the facet it projects 
forwards and completes the median sequence of hypapophyses of the 
centra, being rather larger than any of them. The posterior curve is 
simply inflected downwards and forwards from its apex. 
The scapular arch—(See PI. I)..—The three elements that constitute 
this arch are all represented, and all independent or free bones; the 
coracoids articulate with the sternum and scapule; coracoids and clav- 
icle, connected by ligaments, lend their share to form or strengthen the 
shoulder-joints. The coracoid, comparatively large and strong, forms 
in the usual manner an arthrodial joint of restricted movement with the 
sternum, its lower end being in the coracoid groove on the anterior part 
of that bone. The inner angle of its base is about 2 millimetres from 
the mesial line, and 4 millimetres intervening between it and its fellow 
of the opposite side in the groove. This extremity is broad, its outer 
angle being beneath the third sternal rib at its point of meeting the 
costal border; it is compressed from before backwards. The articular 
facet, looking downwards, backwards, and a little inwards, is trans- 
versely concave, with a slight dividing ridge, running antero-posteriorly, 
converting the general concavity into two smaller ones. The coracoid 
when in position is produced upwards, forwards, and outwards, making, 
with the vertical line through its base, rather an acute angle. <A limited 
portion of the middle third of the bone only is subelliptical on section 
and at all shaft-like, due to the fact that the coracoid in this bird being 
perhaps less than the average length as compared with the size of the 
bird, and, secondly, to the unusually enlarged extremities, features ob- 
servable, more or less, in Raptores generally. The anterior groove of 
the upper extremity, that is arched over by the head of the clavicle 
above, is deep, and occupies fully the upper third of the bone. The co- 
raco-clavicular process springs, thin and compressed, from the inner 
1Jt will be seen that in this figure, corresponding limbs, and other parts that are 
alike on either side of the body, have not been reproduced, it being thought the bet- 
ter way, as the bones on the side towards the observer would necessarily obscure the 
more remote ones, complicate the figure, and show nothing additional, 
