MACKOTHERITJM 349 



humerus differs from that of the ant-eaters and armadillos by 

 its greater length in proportion to its breadth, and by the 

 peculiar flattening from before backwards of its lower half, 

 and especially at the condyles, above which it is expanded 

 transversely by both external and internal supra-condyloid 

 ridges. It is not perforated above the inner condyle, as the 

 same bone is in both the Manis and Orycteropus. In the 

 degree to which it departs from the type of the ant-eaters it 

 approaches that of the Megatherioids and sloths — viz., in its 

 relative length, flattening at the distal end, and the imperfo- 

 rate character of that end. The radius also presents a sloth- 

 like character in its greater proportionate length, which 

 exceeds that of the humerus ; and in the compression of its 

 lower slightly-expanded end. In both the Pangolin and 

 Orycterope, the radius is shorter than the humerus. The 

 ulna differs likewise from both that of the Pangolin and 

 Orycterope, and still more from that in the Armadillos by the 

 much smaller development of the olecranon, whereby, again, 

 it more resembles that of the sloths. The femur is relatively 

 longer and more slender than that of the terrestrial and fos- 

 sorial Edentata ; it has not the third trochanter which charac- 

 terizes it in the Orycterope, nor so marked a development of 

 the great and small trochanters as in the Pangolin. In the 

 flattened form of the shaft of the femur, and the position of 

 the rotular surface near one side of the distal end, it resembles 

 the femur of the Megatherium and Mylodon. It is shorter 

 than the humerus ; whereas, in both the Pangolin and Oryc- 

 terope the femur is longer : in this respect the femur of the 

 Macrothere resembles that of the sloths. The great width of 

 the popliteal space dividing the condyles is an edentate and 

 more especially a megatherioid character. The internal con- 

 dyle is much broader than the external one, as it likewise is 

 in the Megatherioids ; it is certainly with the femur of the 

 latter family of the Edentata, rather than with that of the 



