334 A NEW MYLODON. 
Scapula.— Neither scapula is complete but the fragments put together 
supplement each other. The general form and structure are similar to what 
Owen has described and figured for MW. robustus, but the dimensions differ slightly 
as shown by the following: — 
M. Ropustus M. GARMANI 
Point of coracoid arch to anterovertebral angle =a 290 
Glenoid cavity to vertebral border, opposite spine — 325 
Greatest length of glenoid cavity 127 113 
Greatest breadth of glenoid cavity 76 783 
Longest diameter of supraspinal aperture formed 
by union of acromion and coracoid 127 150 
Shortest diameter of same 76 57 
Greatest height of spine 89 84 
Diameter of coracoscapular foramen 25 37 
Long diameter of clavicular facet — 44 
The spine divides the scapular surface nearly in halves, and is highest at the 
point where the arch formed by acromion and coracoid, begins; that is, at about 
30 mm. from the edge of the glenoid cavity. Its external edge is broadly flat- 
tened, 25 to 21 mm. across, then slightly expands to 45 mm. opposite the 
center of the aperture formed by the fusion of coracoid and acromion. In M. 
robustus, this portion is somewhat wider. The remarkable fusion of the acro- 
mion with the so called coracoid is characteristic of the sloths, and the homology 
of the bones shows that the clavicle articulates as usual with the acromion proc- 
ess, which has thus become greatly extended anteriorly and fuses with the 
coracoid. The coracoscapular foramen is somewhat larger than in M. robustus. 
This perforation is present in the anteaters as well as the sloths. Concerning 
the homology of the so called coracoid in the mammals, Ameghino (1909), 
Lydekker (1893), and Howes (1892) have made critical comparisons among 
fossil and living Edentates and conclude that the bone to which this name has 
been applied is not the same as the coracoid of the Reptilia. Lydekker states 
that in the sloth Bradypus, the coracoid forms part of the glenoid cavity, but 
this should be verified. In a specimen of Myrmecophaga, in which the sutures 
of the scapula are still discernible, the coracoid stands directly over the anterior 
portion of the glenoid, but does not actually form part of it, since it is separated 
therefrom by the epiphysis of the scapula, that extends forward underneath it. 
The appearance is at first as if the coracoid formed the anterior portion of the 
articulation, but this is seen on closer examination not to be the case. 
