l80 ANDREWS. [Vol. VII. 



rods. The retina is evidently the same as those I have seen, but 

 differently interpreted, owing to the discovery of nuclei in the 

 blue pigment — which I regard as belonging to the surface of 

 the yellow cells. 



EUNICIDiE. 



Marphysa sanguinea Quatrefages. 



Only two eyes are present, and these are buried deeply be- 

 neath the cuticle on the dorsal surface, one on each side lying 

 as an oblique red mass external to the base of the posterior 

 lateral antenna. 



Even surface views show a clear stalk extending in from the 

 cuticle to the eye, while macerations reveal a most interesting 

 connection of cuticle and lens. The lens is then seen as a clear, 

 highly refracting mass of conical form, with the base connected 

 to the cuticle by a slender cylindrical stalk quite continuous 

 with both cuticle and lens. In potassium hydrate, when the 

 retinal cells are removed, the lens thus appears as a clear, hard 

 mass hanging from the cuticle by a stalk. 



Though approximately conical, the lens is yet irregular in 

 presenting a side lobe from its base, about parallel to the cuticle, 

 so that the large cone is but the major part of a somewhat 

 bifurcated mass having its common base prolonged up to the 

 cuticle as the narrow stalk. 



Though nearly homogeneous, this lens has a clearer axial part, 

 which is not liquid, however, but striated. The entire surface, 

 except that of the stalk, is covered, in such macerations, by 

 slender filaments or clear threads streaming out from the lens 

 towards the retina and ending at the pigmented zone, when that 

 has not been removed. 



Vertical sections that cut the stalk lengthwise (Fig. 34) show 

 the continuity of lens and cuticle, but give an imperfect idea of 

 the shape of the retinal cup. This is, in fact, like the lens that 

 fills it, somewhat bilobed, and its orifice or pupil is occupied by 

 the cuticular stalk only at one point ; elsewhere the epidermis 

 meets over the lens, and clear elongated cells free from pigment 

 pass continuously from one edge of the optic cup to the other, 

 making: an inner cornea. 



