THE NATURAL HISTORY OF MAN 77 



intercostals favors this explanation and indicates the possible 

 reversionary character of this muscle. 



On the inner side of the lower end of the humerus in the 

 fore limb of man there is occasionally an opening, known as 

 the supracondylar foramen, which is regularly found in some 

 of the lower animals, such as the cat, transmitting a large 

 nerve. The occasional appearance of this foramen in man is 

 believed to be a reversion. 



At an early period of prenatal life a pointed projection of 

 the vertebral column as a tail (Fig. 23) is quite evident. 

 During later development this projection is gradually incor- 

 porated within the body so that the terminal part of the verte- 



Jfl 



Fig. 27. Supernumerary nipples of man. n, normal nipple; 

 sn, supernumerary nipple. Redrawn from Wiedersheim, after 

 Ammon. 



