1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 301 



thing in it to remind ns of birds of more distant kinship, as the Alba- 

 trosses. In other respects, however, it presents characters common to 

 all of these, and not a few resemblances with the last-named group. 

 When this sternum is articulated with the shoulder-girdle its fantastic 

 shape is by no means diminished, for the forms of the various bones 

 which compose the latter, and now to be described, are equally curious 

 and decided departures from the more common style of these elements. 



Of the shoulder-girdle (Figs. 33, 34, and 35). — This part of the skeleton 

 is, like so much of the rest of it, thoroughly pneumatic, the foramina 

 occurring at their usual sites. 



The clavicles form a broad (J-shaped arch, and are completely united 

 below, where, at their under side at the median point, they support au 

 extensive facet for articulation with the carina! angle of the sternum. 

 This does away with any such a thing as a hypocleidium proper, still 

 the bone projects slightly over this facet. 



The clavicular limbs are compressed from side to side, broader above 

 than below, with the anterior and posterior borders rounded off. 



A clavicular head is also compressed in the same manner as its shaft, 

 and tapers off as a pointed process. 



The most striking feature about this part of the bone is, however, 

 the extraordinary facet it supports to articulate with the coracoid. 



Either one of these is situate at the outer aspect of a head, upon a 

 promontory of bone there found of a proper form to receive it. The 

 facet is of an elliptical outline, placed vertically, and facing directly 

 backward. iSomethiug of a notch is found between it and the clavicu- 

 lar head, in which occurs a number of the principal pneumatic foramina 

 of the furcula. On the anterior surface, just below the summit of a 

 coracoid, we find a distinct elliptical facet for articulation with a simi- 

 lar one just described for the fourchette. Between this and the ear- 

 shaped glenoid facet considerable of a valley is found. On the opposite 

 side of the coracoidal head we find a group of pneumatic foramina and 

 below these a peculiarly formed scapular process, a spine-like apophysis, 

 which rather gracefully curls upward and then toward the shaft of the 

 bone. 



This latter portion of the bone is subcylindrical and smooth, dilating 

 below into a transverse fan shaped sternal extremity. 



A scapula offers but a very small portion of the articular surface for 

 the glenoid cavity; not more than an eighth of it in the present speci- 

 men. 



The head of the bone then reaches forward and inward, but only the 

 outer two-thirds of this makes an indifferent articulation with the nar- 

 row and roughened border of the scapular process of the coracoid. 



The shaft of the bone is quite stout behind this and somewhat com- 

 pressed in the vertical direction, while posteriorly it flattens out into a 

 broad paddle shaped extremity that finally tapers to a point behind. 

 (Fig. 35.) 



