148 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



i. Muscles of the external ear. These, which are of large size 

 and functional use in quadrupeds, we retain in a dwindled and useless 

 condition (Fig. 20). This is likewise the case in anthropoid apes; 

 but in not a few other Quadrumana (e. g., baboons, macacus, magots^ 

 etc.) degeneration has not proceeded so far, and the ears are 

 voluntarily movable. 



FIG. 20. Rudimentary, or vestigial and useless, muscles of the human ear. 

 (From Romanes, after Gray.) 



2. Panniculus carnosis. A large number of the mammalia are 

 able to move their skin by means of subcutaneous muscle, as we see, 

 for instance, in a horse, when thus protecting himself against the 

 sucking of flies. We, in common with the Quadrumana, possess an 

 active remnant of such a muscle in the skin of the forehead, whereby 

 we draw up the eyebrows; but we are no longer able to use other 

 considerable remnants of it, in the scalp and elsewhere, or more 

 correctly it is rarely that we meet with persons who can. But most 

 of the Quadrumana (including the anthropoids) are still able to do so. 



