Vol. XII. 1 Shufeldt, Osteology of Cereopsis )iovce-hollandice. 22Q 



described above as passing down the ventral aspect of the bone. 

 This Hne is also a boundary one between pectoral muscles, and 

 is present on the keel of the sternum in most ordinary birds. 



The Pectoral Arch or Shoulder -Girdle. — All the bones composing 

 this arch in the skeleton of the Goose now being considered are, 

 in the highest degree, pneumatic. In the scaptdce the foramen 

 is found on its dorsal aspect, in the middle line, close to its cora- 

 coidal articulation. In the coracoids, a group of these foramina 

 is found on the mesial aspect of the superior end of the bone, under 

 the eaves of the overarching head ; and in the os furcula, on the 

 outer side of the free clavicular extremity at its broadest part. 

 It will be noted from this that when the bones of the girdle are 

 articulated, as in life, their pneumatic foramina are all in the 

 neighbourhood of each other and directed toward the foramen 

 triosseiini. 



When duly articulated, the scapulce reach almost as far back 

 as the pelvis, either one of these bones being thick and flatly 

 rounded anteriorly ; bluntly pointed at the distal apex ; arched 

 throughout in that it may conform to the skeletal wall of the 

 thorax ; while the head, anteriorly, articulates with both coracoid 

 and furcula in a manner common to the Anseres generally. With 

 the coracoid of the same side it helps form a commodious glenoid 

 cavity, the boundaries of which, front and back, are thickened 

 and raised. 



The coracoids are big bones in every particular, as they are in 

 all species of wild Geese. Their sternal extremities are very 

 much expanded and flattened antero-posteriorly. As usual, the 

 lower outer angle extends backward as a fairly prominent process, 

 though more so than it is in Olor or Branta. As all the superior 

 parts of the bone are of large proportions, the shaft between these 

 and the expanded lower end is so much shortened thereby that 

 it has the appearance of being but little more than an intervening 

 " neck," which is a condition that by no means exists in all 

 Anseres where the coracoidal shaft is much longer. 



The OS furculum is of the broad, U-shaped pattern, and is entirely 

 without a hypocleidium. In structure it is rather stout, with 

 either, somewhat enlarged, clavicular extremity drawn out into 

 a long, rather sharp, end, which in life, or in the duly articulated 

 skeleton, glides over the antero-mesial surface of the scapula on 

 either side. 



At the arch below, the posterior surface is roundly convex ; 

 but this becomes flat as we proceed toward the clavicular ends. 

 In front the arch is also flat, with a very slight inclination to 

 become concave from side to side. 



In the articulated skeleton this latter surface faces mostly 

 upwards, and is lost on the smooth, flat limb of either clavicle 

 higher up, on their mesial aspects. 



There are no acromial processes present on this os furculum as 

 there are in Branta canadensis, to a very slight extent in Chen, 

 and are conspicuous characters in so many Ducks and Mergansers. 



