IQ2 ANDREWS. [Vol. VII. 



All these lens elements are in life closely packed to form a 

 solid lens projecting towards the cuticle. In sections, this pro- 

 jection is seen to extend up to the cuticle and even, at one 

 point, to pierce it as a dim line or strand differing from the rest 

 of the cuticle (Fig. 52). 



In depigmented sections the retina is a single layer of cells, 

 each bearing a retinal rod. 



Harmatho'e inibricata Malmgren. 



Sections show the same compound lens and its connection 

 with the cuticle. Macerations furnish retinal cells like those of 

 the last animal ; in fact, as far as observed, the eyes in these 

 two species are identical. 



Sthenelais picta Verrill. 



Here again, four dorsal eyes are met with having compound 

 lenses and dark, smoky-black pigment. No connection of lens 

 and cuticle was discovered, but such may well exist. 



In highly magnified views of a part of a depigmented retina 

 (Fig. 53), the continuity of retinal cell and rod is well shown, 

 as also the close application of these rods to the lens elements, 

 with which, moreover, there is some general agreement in 

 number. A few retinal cells have nuclei in the pigment zone ; 

 these cells seem, as those figured, to be crowded in amongst the 

 more common kind, and are not special pigment cells. 



The eyes of the Polynoidse thus furnish additional evidence 

 of the continuity of the various parts of the eye and of its con- 

 nection with the cuticle. They also indicate that the elements 

 of the lens are but the ends of the retinal cells or else formed 

 by these cells individually. 



Graber (2) has represented the composite nature of the lens 

 in PolyncB eleganSy P. areolata, and in Hermione hystrix ; and 

 also shown the continuity of retinal cells and rods. In most 

 other respects his account may be interpreted as above in the 

 case of the Hesionidae. 



