OUR BEST FEATURES 



stitute only a single manifestation of a morpho- 

 logical theme that has a thousand variations, but 

 is everywhere patently evolved from a shark-like 

 prototype. And in particular this region yields 

 most cogent evidence of man's unity of origin 

 with the anthropoid apes. 



The salivary glands under the tongue and in 

 the sides of the cheek and throat afford another 

 example of the same kind. Huntington has shown 

 how even the variations in man are obviously 

 related to those of the higher primates. 



ORIGIN AND EVOLUTION OF THE HUMAN LIPS 



Let us return now to the outside of the mouth 



and consider the origin and evolution of the 



human lips. The mouth in the lowest existing 



chordate Amphioxus (Fig. 54) is surrounded by 



short stiff projections. Much the same condition 



obtains in the larval lamprey (Fig. 59B). In the 



adult lamprey the mouth cavity is surrounded by 



a movable ring of cartilaginous plates beset with 



thorn-like teeth, probably a very specialized 



arrangement. In the ostracoderms (Figs. 4, 57) 



of the Silurian the border of the capacious mouth 



cavity was covered with small scales and plates. 



129 



