24 COE 



Body very long and slender, somewhat flattened below, irregular and 

 ungraceful in form, and sluggish in movement. Head slightly broader 

 than rest of body ; snout blunt, posterior extremity of body tapering 

 gradually to a point. 



The common opening of the mouth and proboscis lies ventrally, a 

 little back from the tip of the snout. The cerebral sense organs lie 

 far in front of the brain, and each communicates with the exterior by 

 a canal which opens on the ventro-lateral margin near the tip of the 

 snout. 



Color. Uniform dark green above and nearly white below ; some- 

 times grayish or yellowish green above, and very pale yellowish green 

 below. The color of Alaska specimens is as a rule paler and more 

 grayish green than in Mediterranean specimens. The head is bordered 

 with a narrow band of white, uniform with that of the lower surface. 

 Back of the head is an inconspicuous transverse band paler than the 

 rest of the dorsal surface. The pigment resides wholly in the integu- 

 ment, the muscular layers and other organs of the body being prac- 

 tically colorless. 



Ocelli. The eyes (fig. 3) are characteristically arranged in two 

 groups on each side of the head. The anterior group on each side 



usually consists of 8 to 10 pigment-cups ar- 

 ranged in a single row near the antero-lateral 

 border of the head. These lie deeply imbedded 

 in the tissues of the head, and are much more 

 conspicuous from the ventral surface owing to 

 the presence of much pigment on the dorsal 

 surface above them in ordinary states of con- 

 traction. Each posterior group lies nearly 

 Fig. 3. Emphctonema above the brain and consists of 10 to 20 ocelli 

 gracile. Dorsal view of in an i rre g U lar cluster. The eyes of the pos- 



head to show arrange- .1 1 1 r l.\ j 1 



tenor groups are visible only from the dorsal 

 ment of ocelli. X 12. j 11 *i. .u 



suriace, and are smaller in size than those 



of the anterior groups. The integument may be scraped off so as to 



expose the eyes clearly. 



Proboscis. The stylet apparatus is especially characteristic of the 



species. The basis of the central stylet is very long and slender, and 



is twice to three times as long as the stylet itself. The posterior 



end is sharply swollen into a flattened knob (p1. viii, fig. 3). In 



front of the knob the basis decreases in diameter evenly towards the 



anterior end, except for a slight constriction which occurs at about y$ 



the distance from the posterior end. The anterior portion is slightly 



