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COE 



the head. These are also V-shaped with the angle projecting back- 

 ward on the lateral margins. The ventral limb of each V-shaped fur- 

 row reaches nearly to the opening of the rhynchodseum ; on the dorsal 

 surface the ends of the dorsal limbs are separated by about J/S the 

 diameter of the body in ordinary states of contraction (fig. 8). 



In microscopic sections the V-shaped grooves on each side of the 

 head are conspicuous, because of their differentiated epithelium. In 

 these shallow depressions the epithelial cells are of smaller size, more 

 slender in form, and seem to partake more of the nature of sensory 

 cells. In these grooves the ordinary glandular cells are wanting. In 

 the ventral limb of each V-shaped groove opens the tube which places 

 the cerebral sense organs in communication with the exterior. 



Ocelli. — There are commonly 20 to 32 eyes on the head arranged 

 in 4 more or less distinct clusters, though their relative positions change 

 with the contraction of the head. The two anterior clusters contain 

 about 4 to 6 eyes each, and occupy the antero-lateral margins of the 

 head (figs. 8, 9). The posterior clusters lie directly back of these, 



Fig. 8. Fig. 9. 



Figs. 8 and 9. Paranetnertes carnea. 8. Outline of head from dorsal sur- 

 face showing arrangement of ocelli. The two pairs of lateral indentations indi- 

 cate the lateral and dorsal furrows. X S. 9. Outline of the head when extended. 

 Dorsal surface, showing arrangement of ocelli. X 6. 



and immediately in front of the brain. Each of these clusters contains 

 S to 12 scattered ocelli. An individual from Taku Harbor had 6 

 ocelli in each anterior cluster, and 10 in each posterior one. Another 

 specimen had only 3 or 4 eyes in each of the four clusters, but in this 

 case the ocelli were larger. A specimen from Popof Island had 3 

 large eyes in each anterior, and 6 to 8 in each posterior cluster ; one 

 from Virgin Bay had 6 in each anterior, and 7 in each of the others, 



