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JAMES ROLLIN SLONAKER 



The free margin of the nictitating membrane is composed of 

 a stiff and firm band of dense connective tissue arranged so as 

 to form a plait-Kke structure on the anterior surface at the free 

 edge. This firm band I have called the marginal plait of the 

 nictitating membrane. It thus forms on the anterior surface of 



Fig. 6 Enlarged" camera outline drawings, showing the marginal plait of the 

 nictitating membrane extended {A) and compressed (B). Ce, conjunctival 

 epithelium of the cornea; Le, epithelium of the lid; Mp, posterior edge of mar- 

 ginal plait; Ne, epithelium of nictitating membrane. 



the third lid a scoop-like projection, extending anteriorly the 

 entire length of the margin. A cross-section of this plait is 

 shown in figure 6 and plate 10, figures 57, 58, 61. In cross-sec- 

 tion the plait resembles the barb of a fish hook. The posterior 

 margin, which corresponds to the free margin of the nictitating 

 membrane, is thin and closely applied to the corneal surface. 

 As the nictitating membrane is pulled over the front of the eye 

 the margin of this plait is somewhat pressed downward against 



