50 PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 



short, broad plate, with head and tubercle coalesced, and articulating 

 directly with the sternum. The succeeding ribs are long, broad and 

 laterally compressed, with vertical groove and prominent posterior border, 

 somewhat as in Tatu. The sternal ribs are completely ossified and form 

 heavy bars of bone, which increase in length posteriorly ; as in Dasypus, 

 five pairs of these ribs join the sternum directly. 



While the sternum is of typically armadillo-like character, it has certain 

 peculiarities. The presternum is a very broad, shield-shaped plate, which 

 suddenly contracts to the junction with the mesosternum ; its anterior 

 border is broadly and quite deeply emarginate, having projections for 

 articulation with the clavicles. On the ventral surface two ridges run from 

 these projections, converging backward, and between them the ventral 

 surface is concave, while that of the broad wings which articulate with the 

 first pair of ribs is convex. The mesosternum consists of four segments ; 

 the shape cannot be clearly made out, but they appear to be like those of 

 Dasypus, broad dorsally and narrowing ventrally. The xiphisternum is 

 also shaped much as in the recent genus, but is relatively broader and 

 more flattened ; anteriorly, it has two well-marked facets for the sternal ribs. 



Appendicular Skeleton.- -The scapula is large, with broad blade un- 

 equally divided into a larger prescapular and smaller postscapular fossa, 

 and with postero-superior angle extended into a broad, curved sickle- 

 shaped process, which is relatively larger than in Dasypus. The neck is 

 broad, the coraco-scapular notch much shallower than in the latter or 

 Priodontes, and the coracoid border is raised, making the prescapular fossa 

 more deeply concave than in either of the recent genera. The spine is 

 high and its free border is turned back at nearly a right angle, making 

 the border very wide, much wider than in Priodontes, in which something 

 of the same kind occurs. At the level of the glenoid cavity the spine 

 gives off a triangular metacromion. As is usual in this order, the acromion 

 is very elongate, though not in such an exaggerated degree as in the last 

 named genus, and is of a different shape, not being so much compressed, 

 while its external surface is broader than in Dasypus. The raised glenoid 

 border makes a second spine, which is considerably more prominent than 

 in any recent genus with which I have been able to compare it. The 

 coracoid is remarkably long and is a simple, curved, antero-posteriorly 

 compressed hook, which, though not so broad, is otherwise much larger 

 than in Priodontes. 



