COE: NEMERTEANS OF WEST AND NORTHWEST COASTS. 167 



Color. — General color of body yellowish, of a great variety of 

 shades in different portions of the body and in different indi- 

 viduals. Commonly pale yellow, sometimes with a tinge of orange 

 anteriorly, and deep ocher throughout remainder of body. Mar- 

 gins of head paler. Some are deep ocher anteriorly, with a sharp, 

 median, dorsal, longitudinal white line extending through anterior 

 half of esophageal region, while remaining portion of esophageal 

 region is greenish ocher, and intestinal region dull orange. Ven- 

 trally the color is dull whitish on head and in anterior esophageal 

 region, then greenish ocher back as far as intestinal region which is 

 of same orange color as dorsal surface, but somewhat duller. 

 Smaller specimens are commonly much paler in color. Other indi- 

 viduals are of duller colors with dark buff intestinal regions. Still 

 others are golden brown anteriorly (PI. 3, fig. 30), with a tinge of 

 yellowish orange on the head ; intestinal region ocher, buff, or olive 

 brown, sometimes showing a median dorsal longitudinal stripe of 

 darker, more brownish color when filled with mature sexual prod- 

 ucts. Brain region indicated by its more rosy color ; lateral and 

 anterior margins of head very pale or colorless (PI. 3, fig. 30). 



Size. — Small, pale-colored individuals 8-15 mm. long; others 

 20-40 mm., while those from deeper water are often 80-120 mm. 

 in length, with a diameter of 2-3 mm. 



Ocelli. — • On each side of tip of head is a transverse row of 

 irregular pigment masses indefinite in shape, size, and number, and 

 varying in color from blood-red to purple or black. Commonly 

 three to seven irregular groups of pigment granules on each side. 

 Most anterior ocellus commonly is much larger than any of the 

 others, while the three or four posterior ones are represented by 

 minute dots only. Ocelli often fragmented, and scattered as 

 irregularly clustered pigment granules. Color of ocelli usually 

 purple or reddish in individuals dredged from among red sea- 

 weeds. 



Proboscis. — Proboscis sheath extends nearly to end of body. 

 Proboscis pale yellow; attached to dorsal wall of sheath at the 

 posterior end of esophageal region by a powerful retractor muscle. 

 In this same region circular muscles of proboscis sheath extend 

 ventrally to surround the esophagus with a rather thick layer of 

 circular muscles, forming an inner circular muscular layer of the 

 body walls, as in Micrura alaskensis and Zygeupolia littoralis ; this 



