Lewis. — Nervous Syst. Polychaeta. 



PLATE 3. 



Figs. 17, 18. Sections of hypodermis, each passing through a single sense organ, 

 and showing sensory hairs. Vom Rath preparations. X 640. 



Fig. 19. Piece of removed cuticula, highly magnified, and showing the area 

 over a sense organ. The minute circles within the circular area mark 

 the positions of pore canals accommodating the sensory hairs. The 

 small circles outside the area represent gland pores. X 1000. 



Fig. 20. Piece of removed cuticula from the first segment, showing the mosaic 

 patches upon which the sense organs are found. These are indicated 

 by concentric circles, some of the gland pores by a small circle and 

 cross. X 120. 



Fig. 21. Cross section of nerve cord and body wall, to show topographical rela- 

 tions. Vom Rath preparation. X 640. 



