THE EVOLUTION OF MAN 



is represented among mammals by the duckbill, 

 the young of which licks, during its stay in the 

 pocket, the percolating juice of a gland. 



On the other hand, it cannot be denied that 

 the general construction of a duckbill has many 



A HUMAN EMBRYO, 



in the middle of the fifth week of its development. It is 

 strongly magnified, its natural size being about one centimeter. 

 Note the gill-opening on the neck, the fin-like limbs, and the 

 plainly developed tail. 



points resembling those of saurians, in other 

 words, of reptiles. The only marked difference 

 in their skeleton is the way in which the lower 

 jaw is attached to the skull. This separates rep- 

 tiles and mammals very distinctly. Indeed, the 



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