Finally, a word on the origin of the lens and the relative position of the lens and retina. The lens and retina in this eye are evidently not developed from an outer and an inner half, respectively, of the invaginated and pinched-off lens-retina sphere (as is true for the distal complex eye) but from proximal and distal halves respectively. It is also quite easy to understand the connection of the lens in this eye with the supporting membrane. Since the cells of the ectoderm of the club can in many instances be seen to extend to the basement membrane, or supporting lamella, the cells of the lens, which arise from the ectoderm, simply remain in connection with the basement membrane, this becoming thickened to form a support for the lens. That the lens of the distal complex eye has lost its connection with the basement membrane is evidently due to the fact that the lens is formed from the outer half of the lens-retina sphere. The cells of the lens are by this so far separated from the basement membrane as to lose their connection with it. Schewiakoff also notes the fact that the lens and retina of the proximal complex eye are developed from proximal and distal halves of the lens-retina sphere. He further supposes that the portion of the basement membrane that acts as a support to the lens takes the place of the capsule in the distal complex eye. This latter supposition I do not think probable, since the supporting lamella does not form a distinct covering to the lens on its retinal side. _The Simple Eyes._--Since the shape and position of these eyes have already been described (Claus, Schewiakoff, Conant), I shall not tarry long in this respect. Speaking generally, these eyes are flask-shaped (Fig. 12), the proximal pair quite so, while the distal pair are drawn out in the transverse diameter of the club. These eyes are invaginations of the surface epithelium and the shape of the cells lining these invaginations is quite like that of the epithelial cells, except that their distal portions (bordering the lumen of the invagination) are heavily pigmented. The proximal walls (Fig. 12, left side) of the distal pair are heavier pigmented than the distal walls and the proximal pair of eyes. Schewiakoff calls attention to this point. The pigmentation is, furthermore, not only heavier, but the pigmented portion of each cell is much longer in the proximal walls of the distal eyes (indeed, the cells are longer) than in the distal walls. The significance of this I do not understand. Indeed, I am inclined to believe that in life all these eyes are pigmented quite alike and that it is the reagents used that alter or dissolve the pigment in certain places. Yet, the fact that the cells of the proximal walls of the distal eyes have their pigmented portions nearly double the usual length, shows some deeper significance.