E. W. BERGER ON THE CUBOMEDUSJS. 61 



are evidently not developed from an outer and an inner half, 

 respectively, of the invaginated and piiiched-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. 



TJie 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 invag- 

 iiiation) 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 



