46O SHAFER 



of larger facets. Longitudinal sections of the ommatidia of 

 both these parts of the eye may be obtained by making vertical 

 cross-sections, or by making longitudinal sagittal sections of 

 the head. Fig. 2 shows a vertical section passing through both 

 the upper and the lower portions of the eye. Most of the eye 

 elements are cut longitudinally. A few in the region a, of the 

 upper part of the eye are represented in diagonal cross-section. 

 A glance at the figure makes clear the deeply pigmented condi- 

 tion of the narrow eye elements of the lower half as contrasted 

 with the less pigmented larger elements of the upper half of 

 the eye. There is no gradual transition in the pigmentation or 

 in the size of the eye elements. The line of division is as 

 sharp within the eye as it appears in the outside facet view. 

 No septum marks the division ; but with the first larger orama- 

 tidial element, passing toward the upper part of the eye, the 

 deep black iris pigment stops and a brownish less dense iris 

 pigment begins. This is true also of the deeper seated pig- 

 ments, but these are a little darker in color in the large element 

 half of the eye than in the iris pigment in the same part. Figs. 

 3 and 4 show some of the details of structure of the upper and 

 lower parts of the same eye. The corneal region is made up 

 of hexagonal lens-like segments each of which maybe called a 

 corneal lens. In vertical section each lens is seen to consist of 

 a thin cuticular portion and a thicker stratified layer just beneath. 

 The cuticular portion takes and retains nuclear stains well. The 

 under portion takes stains readily enough but gives them up easily. 

 No hypodermal cells or nuclei have been observed in the eye, but 

 the bases of the pseudocones lie close to the under portion of the 

 lens. The cells which compose these pseudocones have lost their 

 identity entirely in the lower portions, and nearly so in the 

 upper, outer, larger portion of the cones. However, in the 

 extreme upper ends, the cone cells have each secreted a denser 

 curved plate-like body within itself, and this stains deeply. 

 Four of these may be found in each pseudocone. Two are 

 shown in the longitudinal sections at en. Each plate appears 

 to surround a cell nucleus. In the case of the pseudocones of 

 the small ommatidial elements, cross-sections made just below 

 the little plates mentioned show four cells as represented in 



