NEMERTEANS 165 



the posterior extremity of the body, and are sharp and conspicuous 

 throughout. The diameter of each stripe is perhaps one-sixth the di- 

 ameter of body, and the two are separated about twice the diameter of 

 each. In ordinary states of contraction the stripes are not quite as 

 widely separated as are the ocelli, so that they pass medially to the 

 latter. In preserved specimens the stripes retain their rich brown color 

 even after imbedding in paraffin. 



Ocelli. The four ocelli are of moderate size, and, as in many re- 

 lated species, usually occupy the corners of a square (pi. xiv, fig. 6). 

 They are situated deep in the tissues of the head. There is no trace 

 of pigment between the two ocelli of the same side. 



Proboscis. Presents few deviations from the normal type, and, as 

 usual, is provided with ten nerves. Basis is of very small size, rather 

 slender, and but slightly enlarged posteriorly. Its average length is 

 only about .O5-.O7 mm. and its width .O2-.O25 mm. The central stylet 

 is rather slender (pi. xxi, figs. 13, 14) ; each of the two lateral pouches 

 contains two or three accessory stylets. Proboscis is attached a little 

 in front of brain ; proboscis sheath does not extend quite to posterior 

 end of body. 



Body Walls. The pigment which gives the brown color to the 

 longitudinal dorsal bands (pi. xxn, fig. ^pig) is conspicuous in every 

 transverse section of the body. It is not situated in the integument, 

 but occupies the inner portion of the longitudinal muscular layer. 

 Throughout the whole body, except in the head and most anterior 

 esophageal region, the anastomosing pigment cells largely obscure the 

 muscular fibers in the region where they are situated. This causes the 

 longitudinal muscular layer to appear interrupted by an elongated dark 

 mass on each side of the proboscis sheath. Just back of the brain, 

 where the muscular layer is thickest, the pigment masses lie on the 

 internal border of this layer, but farther back they occupy its whole 

 thickness (pi. xxn, fig. 4). 



Submuscular glands appear only in anterior esophageal region, and 

 are but little developed. 



Alimentary Canal. A broad intestinal caecum extends forward 

 through about half the length of esophageal region. It lies beneath and 

 beside the esophagus, which opens through its dorsal wall posteriorly. 



Nephridia. Situated in the middle portion of the esophageal re- 

 gion. A single pair of efferent ducts passes immediately above the 

 lateral nerves to open on the surface of the body just beneath the lat- 

 eral margins. The efferent ducts are situated only a few sections pos- 

 tterior to the anterior end of the intestinal caecum. 



