LATERAL AND CENTRAL EYES OF SCORPIO AND LIMULUS. 189 



The eye-capsule or ommateal-capsule (fig. 8 d') is, as 

 in the case of the lateral eye, a continuation of the well-de- 

 veloped basement membrane (fig. 8(/), which marks off the 

 hypodermis of the prosomatic shield from the subjacent con- 

 nective tissue. It is finely laminated, and devoid of nuclei. 

 The septum (fig. 8 n), which divides the vitreous body from the 

 rest of the ommateum, is continuous with and part of the cap- 

 sule. Von Graber has the merit of having discovered this 

 septal membrane. 



The cells of the vitreous body (figs. 8. 9, 11 o) are closely 

 similar to those of the general hypodermis, with which they are 

 in direct continuity ; but they are devoid of pigment. 



The long axes of these cells are curiously bent in one portion 

 of the vitreous body (see fig. 8). Instead of radiating in lines, 

 which would meet if continued at some geometrical centre re- 

 lated to the curved surfaces of the cuticular lens, the vitreous 

 cells exhibit a bending towards the side marked b in the figure, 

 which possibly has some relation to the optical axis of the eye. 

 This seems to lead to the inference that the optical axis differs 

 considerably from the geometrical axis of the lens; and this 

 inference is confirmed by the one-sided development of the 

 hinder part of the ommateum (see figs. 7 and 9). 



There is no concretion or formation of refringent substance 

 in any of the cells of the vitreous body. 



The RETINAL BODY may be divided into the layer of nerve-end 

 cells and the layer of nerve-fibres — interspaces, and the whole 

 inner surface of the ommateal capsule being filled in by intru- 

 sive pigmentary connective tissue. 



The NERVE-END CELLS abut upon the septal membrane, which 

 divides the vitreous body from the retinal body. The opposite 

 extremity or filamentary extremity of the elongated nerve-end 

 cells does not come into such close proximity with the ommateal 

 capsule as in the lateral eyes ; a large mass of intracapsular 

 nerve filaments (fig. 8 q) separates the nerve-end cells from the 

 capsule. In the lateral eye this mass of intracapsular nerve 

 filaments does not exist, the nerve filaments perforating the 

 capsule more immediately than they do in the central eye. 



