354 BUREAU OF AMERICAN ETHNOLOGY [bull. 52 



"Notwithstanding all the other human characteristics which the 

 femur of Tetraprothomo shoAvs, the presence of this large lateral ses- 

 amoid would have furnished sufhcient cause to doubt that the bone 

 belonged to a primate, if it were not for the circumstance that the 

 same feature is at times obserA^able in the anthropomorphs, especially 

 the orang, and above all for the fact that it occurs also, though very 

 rarely, in man. With the discover}^ of the Tetraprothomo there is now 

 explained the appearance of the bone in man and the anthropo- 

 morphs. It is a case in man of atavic reappearance of a character 

 which was proper to liis more immediate ancestors. . . . 



"In the TetraprotJiomo the anterior border of the cavity for the 

 sesamo-femoral ligament is prolonged upward in the form of a rough 

 crest, which terminates in a supracondylar tubercle of an extraor- 

 dinary development. In man this tubercle is very small or is replaced 

 by a simple rugosity, but there are cases in wliich it acquires a devel- 

 opment as considerable as in the TetraprotTiomo. It is therefore a 

 case, as in the preceding instance, of atavic regression. This tubercle 

 serves for the insertion of the medio-superior tendon of the external 

 gemellus. Now, the great development of the tubercle and the rugosi- 

 ties which accompany it up to the corresponding ligamentary impres- 

 sion of the external tuberosity indicate great development of this 

 muscle. It has already been seen above that the gemellus internus 

 was also much developed. 



"This great development of the gemelli or gastrocnemii muscles is 

 exceedingly important, because the latter exercise the principal role 

 in biped progression. It is for this reason that they present greater 

 development in man than in any other mammal, without excluding 

 the anthropomorphs. It is the great development of the gemelli and 

 of the soleus which produces the enlargement of the limb known as 

 'pantorillas,' which under this form and at the present time are fea- 

 tures exclusively of man. It being demonstrated that the Tetra- 

 prothomo possessed gemelli muscles as well developed as they are in 

 man, it must therefore have possessed also real ' pantorillas ' and in 

 consequence a biped walk and erect position." 



The inter-condyloid fossa "does not seem to present any differences 

 from that of the human femur, either in relative size or in disposition, 

 or they are, in view of the differences which the features show in man 

 according to races and individual varieties, insignificant and without 

 importance. . . . 



"The patellar and condylar surfaces form a figure which narrows 

 from the back forward in a considerably more accentuated degree than 

 in the human femur. This difference is due to the fact that in the 

 Tetraprothomo the patellar surface is more narrow and that the con- 

 dyles extend considerabl}^ farther backward, from wliich it results that 

 the pateUo-condylar field is of greater antero-posterior than trans- 



