NO. 13 COE : REVISION OF THE NEMERTEAN FAUNA 287 



Size. 10-15 mm long and 0.5 mm in diameter when mature. 



Color. Pale red or yellowish, with deep red blood. 



Ocelli. 4 very small, crescentic ocelli form the corners of a rectangle 

 immediately in front of brain; the 2 ocelli of the same side are much 

 closer together than the distance between either pair (Fig. 38) ; situated 

 deep in tissues of head beneath cephalic musculature. 



Proboscis. Proboscis sheath limited to anterior third of body (Fig. 

 38). Proboscis very short and small; muscular layers very thin; anterior 

 chamber only 1/4 to % as long as body, armed with small, pear-shaped 

 basis about the same length as the slender stylet and with two lateral 

 pouches each containing 2-3 stylets. In each of 2 specimens available for 

 study the basis measured only 0.04 mm in length. There are 10 pro- 

 boscidial nerves. 



Vascular system. The 3 longitudinal vessels and the cephalic loop are 

 very conspicuous in the living worm because of the bright red color of 

 the blood. Color present principally in corpuscles, but plasma is also 

 tinged with red. Walls of blood vessels remarkably thick and firm. 



Nephridia. Limited to anterior portion of esophageal region. The 

 branching tubules lie close beneath the body musculature both above and 

 below the nerve cords, but the efferent ducts open on the ventrolateral 

 aspects of the body. 



Cephalic glands. Voluminous, extending posteriorly to brain region. 

 In addition to pair of main ducts opening at tip of head are very numerous 

 smaller ducts opening directly on all surfaces of the head. 



Cerebral sense organs. Small, less than yi the diameter of the ventral 

 ganglia. Situated close beneath anterolateral borders of brain; open by 

 large ducts to ventrolateral surfaces of head. 



Lateral nerve cords. With single fibrous core. 



Alimentary canal. Mouth and proboscis opening united; esophagus- 

 stomach rather long, with correspondingly long intestinal caecum, latter 

 with pair of broad diverticula extending anteriorly to posterior border 

 of dorsal ganglia. 



Reproduction. Hermaphroditic and protandric; gonads extend for- 

 ward almost to brain region ; 5-8 anterior gonads function as spermaries, 

 the remaining 20 or more pairs as ovaries. 



Habitat. In mud and beneath dead vegetation between tidemarks. 



Distribution. At present known only from Mission Bay, San Diego, 

 California. 



