IO 



APES AXD MONKEYS 



In diagram Xo. 4 we have the lines and angles of reptiles. 

 In these it will be seen that the facial axis fg and the cer- 

 vical axis hi are almost horizontal. The craniofacial and 

 gnathic angles have been correspondingly widened. 



Man standing erect has the greatest range of vocal 

 powers of any animal. He also has the greatest control 

 over them. In vocal range the apes come next in order. 



Diagram No. 4 



As we descend the scale from man through apes, monkeys, 

 lemurs, and lemuroids, ultimately ending in the reptilian 

 forms, we find the vocal powers restricted in scope and 

 degraded in quality, until in the lowest reptiles they are 

 lost in a mere hiss. 



Concurrent with the variations described, the longitudi- 

 nal, vertical, and transverse axes of the brain also change 

 their proportion in a like degree. The angles formed by 

 the plane of the vocal cords with the axis of the larynx 

 undergo a corresponding change. A just deduction from 



