THE DESCENT OR ORIGIN OF MAN 



35 



cases, the margin had been folded inward in the normal 

 manner, an inward projection must have been formed. I 

 may add that in two other cases the outline still remains 

 somewhat pointed, although the margin of the upper part 

 of the ear is normally folded inward — ^in one of them, how- 

 ever, very narrowly. The following woodcut (No. 3) is 

 an accurate copy of a photograph of the foetus of an orang 

 (kindly sent me by Dr. Nitsche), in which it may be seen 

 how different the pointed outline of the ear is at this period 

 from its adult condition, when it bears a close general re- 



Fie. 3.— Foetus of an Orang. Exact copy of a photograph, showing the form 

 of the ear at tnis early age. 



semblance to that of man. It is evident that the folding 

 over of the tip of such an ear, unless it changed greatly 

 during its further development, would give rise to a point 

 projecting inward. On the whole, it still seems to me prob- 

 able that the points in question are in some cases, both in 

 man and apes, vestiges of a former condition. 



The nictitating membrane, or third eyelid, with its ac- 

 cessory muscles and other structures, is especially well 

 developed in birds, and is of much functional importance 

 to them, as it can be rapidly drawn across the whole eye- 

 ball. It is found in some reptiles and amphibians, and in 



