1905.] OSTEOLOGY OF THE EURYLHMIDA. AT 
is long, slender, gently arched, and bears a large hypocleideum, 
roughly quadrangular in form, and articulating with the anterior 
edge of the carina. The free ends of the furcula are expanded to 
form flat plates articulating with the acrocoracoid, procoracoid, and 
acromion process of the scapula (text-fig. 14), thus enclosing the 
JSoramen triossewm. 
In the form of the sternum and shoulder-girdle the Eurylemide 
closely resemble the Cotingide, especially in the form of the spina 
externa, which is simple, and thereby differs from the typical 
Passerine form wherein it is forked. In the Eurylemide this 
process is more or less spike-shaped, whereas in the Cotingide it 
appears to be generally flabellate. In Chasmorhynchus the 
posterior sternal notches are not so deep as in the Eurylemide. 
The hypocleideum articulates nearer the antero-ventral angle of 
the carina; and the coracoids do not develop the internal basal 
flange found in the Eurylemide. 
Text-fig. 14, 
Portion of the shoulder-girdle of Calyptomena, to show the meeting-point of the 
scapula, coracoid, and clavicle, forming the inner wall of the foramen triosseum. 
se., scapula; ac., acrocoracoid ; f., furcula. 
In the relations of the articulations between the procoracoid, 
furcula, and scapula, where these unite to form the foramen 
triosseum, the Hurylemide are distinctly Passerine, though this 
arrangement also obtains among the Picide—a fact of some 
significance. 
In Calyptomena, for instance, the acromion process of the scapula 
extends downwards along the anterior border of the free edge of 
the procoracoid, and affords an articular surface cephalad, for the 
posterior angle of the expanded free end of the fureula. In 
Chasmorh ynchus this articulation for the furcula is markedly 
increased ; and this increase apparently reaches its maximum in 
the Corvide, where the acromion forms a long beam-like roof 
to the foramen triosseum, and a very extensive articular surface 
for the furcula, 
