383 



THE AMERICAN MUSEUM JOURNAL 



bone. It has a special interest, besides, 

 since it possessed another very impor- 

 tant striicture in higlier vertebrates — 

 namely, an eardrum, which was doubt- 

 less stretched upon the bony rim behind 

 the eye-sockets. 



The Tejn lizard represents a still 

 higher grade of organization, the next 

 step toward the mammals in one direc- 

 tion and toward the birds in another. 

 It is an active, carnivorous animal, and 

 its face is well protected by a mask of 

 scaly skin. The bony mask is also still 

 there, nnder the skin; but here is a 

 ])()int most important to remember, that 

 if you took off the scaly skin of the 

 face in this reptile, you would not find 

 any facial muscles Ijcneatli tlu> skin, 

 such as are present in our own face. 

 It is only on the under side of the jaws 

 and lliroat that vou would find a hiver 



Tlie faci.al musdes are supplied by branches 

 of the seventh or facial nerve, which issues from 

 the skull behind and below the ear. It is be- 

 lieved that the throat muscle in remote ancestors 

 of mammals spreads upward between the bone 

 and the skin, carrying the seventh nerve with 

 it, and that as the muscle branched, the nerve 

 also branched again and again, producing the 

 highly mobile sensitive face of man. From Cun- 

 ningham's Anatomy 



of muscles beneath the skin. In the ab- 

 sence of true facial muscles all reptiles 

 are inferior in rank to the mammals, 

 where facial muscles first appear. Birds 

 have the immol)ile nonmuscular face of 

 rei)tiles, further masked l)y a horny ])eak 

 or bill ; l)ut the mammals have soft mus- 

 cular lips and a muscular layer about 

 the nose, eyes, forehead, and cars. 



One of the greatest gaps in the 

 whole record of the evolution of the 

 face consists in this, that in spite of 

 the relative abundance of living relies 

 that preserve successive stages in the 

 evolution of the skull itself, there is no 

 animal known which has an intermedi- 

 ate type of face between the immobile 

 iKniinuscuhir face of reptiles and the 

 mobile muscular face of mammals. In 

 spite of this, comparative anatomy fur- 

 nishes fairly clear evidence as to the 

 exact process by which the one did 

 evolve into the other. 



The facial muscles of a typical mam- 

 mal, a lemur {Pro pith ecus), for in- 

 stance, correspond with the facial 

 muscles of man. They include the pla- 

 tysma covering the throat, the orbicu- 

 lar muscle around the eye, the muscles 

 of the nose, the muscles that lift the 

 \\\^. the muscles that draw back the cor- 

 ners of the mouth, and the buccinator, 

 which is of great use not only in blow- 

 ing a trumpet, as its name suggests, 

 but also in protruding the lips and in 

 jmshing the food aljout inside the 

 mouth. 



All these various muscles of the face 

 in man are innervated by branches of 

 the seventh or facial nerve. The facial 

 nerve comes out from behind the ear, 

 and turns forward, one branch going 

 to the platysma muscle on the surface 

 of the throat and the other in numer- 

 ous branches and sub-branches, like a 

 vine and its divisions, passing forward 

 to supply the muscles of the face. This 



