HRDLieKA] SKEL.ETAL EEMAINS OF EARLY MAN 357 



Moreover, it is easy to perceive that in the Tetraprothomo this region 

 was on the way of transformation in the direction toward the form 

 characteristic of man." 



The shaft of the Tetraprothomo femur presents "all the distinct 

 curves of the human femur" and ''a femur which presents Reunited 

 the conjunction of these curves can be regarded with certainty as 

 proceeding from a primate of erect position. What is above all 

 surprising and worthy of reflection is that in this case also the human 

 characteristics mentioned are considerably more accentuated in the 

 femur of the Tetraprothomo than in that of man. . . . 



"The region of the greatest importarffce is the posterior surface of 

 the shaft, because it carries the linea aspera, which is one of the 

 characteristics which separate the femur of man from that of all the 

 rest of the mammals, including the anthropomorphs, and whfch stands 

 in correlation with the erect position. . . . 



"In the femur of the Tetraprothomo the linea aspera in its general 

 form is identical with that of the human femur, differing only by its 

 scarcely smaller development and some other secondary details. . . . 



"That being so, as the same organs must correspond to the same 

 functions, the linea aspera of the femur of the Tetraprothomo must 

 have subserved the same functions as the linea aspera of the human 

 femur. In consequence, the Tetraprothomo was a biped of a perfectly 

 erect position." . . . 



The nutritive foramen is situated (with a shght difference in height) 

 and directed as in man. 



The popliteal space is convex in the transverse direction, instead 

 of being slightly depressed or concave as in man. "This latter con- 

 formation, although very rare, is also observed in the femur of 

 man. . . . There appears, however, in the middle of the convexity a 

 small depression from above downward, Avith a rough surface and 

 some small vascular perforations. This depression represents the 

 commencement of a process of formation of a depression much more 

 considerable than that characterizing the human femur." 



The shape of the shaft at the middle is subtriangular, showing the 

 relation of the bone to that of man. "In commencing the examina- 

 tion of the linea aspera, I said already that this is the feature which 

 gave the body of the bone in the median part of its length a trans- 

 verse section, with its larger axis in the antero-posterior direction 

 while in all other mammals the section in the same region shows 

 always a greater axis in the transverse direction (I have already men- 

 tioned the exception to this presented by some ungulates and also 

 the fact that these have no value whatever in this question)." 



On the succeeding pages (152-158) Professor Ameghino gives 

 a nimiber of sections of the shaft of the Tetraprothomo and other 

 femora. It seems that some of the figures are not printed strictly 



