PLATE 2 



EXPLANATION OF FIGURES 



Camera-lucida tracings of the outline of the adult fovea. 



6 H, horizontal; V, vertical of the same specimen. X 125. 



7 H, horizontal; V, vertical of a different specimen. X 125. 



8 H, horizontal; T", vertical of the lower portion of the fovea of the same 

 specimen as fig. 7. X 450. 



9 Outlines of the shape of the depression forming the fovea at different levels 

 as seen in sections tangential to the retina or vertical to fig. 6, parallel to the 

 line H-H. X 125. 



a. At extreme bottom of fovea. Diam. vert. .008 mm. hor. .016 mm. 



b. .015 mm. from bottom of fovea. Diam. vert. .016 mm. hor. .048 mm. 



c. .030 mm. from bottom of fovea. Diam. vert. .040 mm. hor. .088 mm. 



d. .045 mm. from bottom of fovea. Diam. vert. .048 mm. hor. .132 mm. 



e. .060 mm. from bottom of fovea. Diam. vert. .066 mm. hor. .144 mm. 



f. .075 mm. from bottom of fovea. Diam. vert. .088 mm. hor. .160 mm. 



g. .090 mm. from bottom of fovea. Diam. vert. .096 mm. hor. .208 mm. 

 h. .105 mm. from bottom of fovea. Diam. vert. .104 mm. hor. .224 mm. 

 i. .120 mm. from bottom of fovea. Diam. vert. .144 mm. hor. .256 mm. 

 j. .135 mm. from bottom of fovea. Diam. vert. .176 mm. hor. .288 mm. 

 k. .150 mm. from bottom of fovea. Diam. vert. .208 mm. hor. .336 mm. 

 1. .165 mm. from bottom of fovea. Diam. vert. .234 mm. hor. .368 mm. 



m. .180 mm. from bottom of fovea. Diam. vert. .300 mm. hor .432 mm. 



This last figure is at the inner surface of the retina. The fovea in this speci- 

 men is thus .180 mm. deep and has a vertical diameter of .3 mm. and a horizontal 

 diameter of .432 mm. at the level of the inner surface of the retina where the 

 depression begins. 



438 



