CHAPTER 10 



THE EYES OF ANNULATA 



The phylum Annulata includes the earthworms ; fresh-water worms ; 

 marine annelids ; the primitive Archi- Annelida (Polygordius) ; certain 

 parasitic and tube- worms, and the leeches. 



Fig. 62. 



Anterior part of the nervous system of Nereis, showing two pairs of eyes, ey. 1 , ey. 2 ; 

 which are connected by short stalks, the optic nerves with br., the supra- 

 oesophageal ganglion or brain ; the brain is connected by two nerve cords, 

 the oesophageal connectives, ces. c, with the infra-oesophageal ganglion, these 

 pass ventrally one on each side of the oesophagus; inf.o.g., the infra- 

 oesophageal ganglia, are continuous behind with the ventral chain of fused 

 bilateral ganglia, and nerve cords, which supplies the viscera and posterior 

 segments of the body. (After Quatrefages — Parker and Haswell.) 



96 



