644 GEOLOGICAL SURVEY OF THE TERRITORIES. 
head and inferior expansion. This flared extremity is quite thin out- 
wardly, stouter within, where it appears to be more of an extension and 
spreading of the shaft in its course downwards. Below there is a nar- 
row crescentic facet for the sternum, and at the upper edge of the ex- 
terior and thin side of the dilated end we find a notch, sometimes a fora- 
men, that appears to be constant. ; 
The upper extremity of the coracoid is an irregular tuberosity, con- 
sisting of a lower, inner, and smaller process for articulation with the 
clavicle, and an upper, superiorly convex head, that curls over mesiad 
to create a fossa, at the base of which we discover a group of various- 
sized pneumatic foramina. Anteriorly the head shows rather a well- 
marked process, into which the ligament coming from the horn of the 
sternal manubrium, of the same side, is inserted. 
To the outer aspect, and below the head, is the reniform and vertical 
facet that, with the scapula and os humero-scapulare, goes to complete 
the glenoid cavity. 
The os humero-scapulare is a free bone, rather larger than the patella, 
found at the upper and posterior angle of the glenoidal process of the 
scapula. It is an elliptical disc, with a peg-like process extending from 
it from behind. The outer surface is concave and articular for the com- 
pletion of the glenoid cavity. This ossicle is held in position by various 
fibrous ligaments stretching from its borders to the scapular arch and 
the humerus.! 
The clavicles are thoroughly fused together, forming one deeply U- 
shaped bone; their cylindrical and curved lengths support at the union, 
mesially and below, a long lamina of bone, in the median plane, that is 
directed upwards and backwards, parallel to the anterior carinal crest, 
to which it is united by ligament in the living bird. Their upper ends 
are expanded and placed in the skeleton flat-wise against the acromial 
process of the scapula and the head and the lower or clavicular process 
of thecoracoid. The acromial process, through its bifurcation, partially 
gers the hind border of this expanded end of the furculum, on either 
side. 
This bone seems to be non-pneumatic, while the coracoids are hollow 
almost throughout their entire extent, having in their composition very 
little cancellous tissue and a thin though firm, compact layer. The scap- 
ul are hollow for some little distance into their blades, to be terminated 
by a cancellous structure, with an external and attenuated outer com- 
pact coat. . 
With the scapula arch in situ, we observe that the coracoids do not 
meet below in the coracoidal groove of the sternum, but approach only, 
on each side, as far as the periphery of the pneumatic foramen at the 
base and behind the manubrium. 
They are directed upwards, forwards, and outwards, at an angle of 
about 45° with the horizontal plane, the skeleton being erect; and, as a 
consequence, we find their upper ends further apart than any other part 
of the bone. 
The aperture between scapula and coracoid is in nearly a right angle, 
and the straight part of the inner scapular borders are parallel, their 
obliquely cut ends alone slightly turning outwards. 
A scapula is 2.5 centimetres long, a coracoid 3 centimetres, the inter- 
clavicular space above being 1 centimetre. 
In Turdus migratorius we find the scapula shorter in proportion when 
| This little bone should be considered as a sesamoidal auxiliary to the shoulder 
girdle, as it increases the articular surface of the glenoid cavity, and never be enu- 
merated as one of the bones of the pectoral limb. 
