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. 



