IQO ANDREWS. [Vol. VII. 



in the Nereidae, and structures found in the Eunicidae in addi- 

 tion. In the case of Odontosyllis, however, we have also evidence 

 of the composite nature of the lens ; a suggestion that it may be 

 only the partly fused ends of the rods, that it is composed of 

 the modified retinal cells themselves. 



No account of the eyes of the Syllidae giving more than the 

 general appearance of lens and pigment appears to have been 

 hitherto published. 



Hesionid^. 



Podarke obscura Verrill. 



The anterior of the four dorsal eyes are, as usual, the larger. 

 The lenses are not prominent, and look outward ; the anterior, 

 also forward ; the posterior, backward. 



The isolated retinal cells are much as in Nereis, and contain 

 a pigment that is red-brown when fresh. 



Even surface views show depressions of the cuticle passing 

 in as hollow stalks to connect with the lens. On section the 

 cuticle actually rolls in at one point, to form a hollow tube 

 (Fig. 49), open to the exterior, but closed by the lens. The 

 inflected cuticle spreads out parallel to the surface, to fade away 

 as the superficial part of the lens next the retinal rods, the 

 relationship of lens and cuticle being as shown on a larger scale 

 in Eunice (Fig. 32). The lens, as in Odontosyllis, has radiating 

 elements, appearing at places to be continuous with the retinal 

 rods ; but it has no special refracting globules in addition. 



Depigmented sections show plainly that each retinal cell ends 

 as a clear rod. There is, moreover, an appearance as of a per- 

 forated membrane marking off the cell bodies from the rods, 

 just as in Nereis and the Eunicidae ; but this is to be interpreted 

 as due to the greater amount of pigment in the superficial than 

 in the axial parts of the cell body and to its sudden cessation, 

 usually, where the rod begins. 



In two cases, a small extra eye was found closely applied to 

 the usual posterior eye upon one side of the head. This eye 

 does not appear directly connected with the cuticle, but is a 

 side lobe of the normal eye, somewhat as found in Marphysa, 

 but more widely separated and independent. 



In Hesione pantherina Graber (2) finds no slender lens-stalk, 

 but a large mass passing from the cuticle into the retinal cup, 



