NEMERTEANS 167 



grooves on the head, or a little behind them. The white space sepa- 

 rating the lateral from dorsal stripes is nearly equal to the width of one 

 of the dorsal stripes. While the color of the stripes is always a deep 

 rich brown (pi. xiv, fig. 5), the whitish ground color is subject to con- 

 siderable variation in different individuals and in different states of 

 development of the sexual products. 



The head is usually pure white except for the brown stripes ; esopha- 

 geal region commonly pure opaque white, although several mature 

 male specimens were pale yellowish or flesh-colored in this region. 

 Intestinal region commonly has a tinge of yellow or of pale salmon, 

 due to the color of the intestinal lobes which show through the other 

 tissues. When filled with mature ova, the intestinal region often has 

 a yellowish or very pale greenish tinge, while the males may be pale 

 flesh colored. 



The ventral is of practically the same color as the dorsal surface, 

 but the effect of intestinal lobes and sexual products is here more 

 marked, so that in the intestinal region there is often a tinge of salmon 

 (from the intestinal lobes), of flesh color, or of greenish yellow (from 

 the sexual products). The color is also affected by the dorsal brown 

 stripes which show through the other tissues to some extent. 



Proboscis whitish ; brain pale yellow in color. 



The four dark brown stripes are quite as conspicuous after preser- 

 vation, and even after imbedding in paraffin, as they are in life. 



Ocelli. The four medium-sized ocelli are arranged nearly in the 

 form of a square in ordinary states of contraction of the head. Their 

 relative position to the brown dorsal stripes is very variable, be- 

 cause they lie so deep in the tissues of the head as to be unaffected 

 by the contraction of the superficial tissues in which the pigment 

 of the stripes resides. Commonly, however, they lie in or just lateral 

 to the brown stripes the anterior pair lying near the anterior ends 

 of the stripes, and the posterior pair about on a level with the lateral 

 oblique grooves, as these appear on the margins of the head (pi. xiv, 



%. 5)- 



Size. A small species, averaging only about 8-12 mm. long, and 



less than I mm. in width, when sexually mature. 



Proboscis, Proboscis sheath extends to posterior end of body. 

 Basis of central stylet bell-shaped, short, much enlarged and rather ab- 

 ruptly truncated posteriorly (pi. xx, figs. 12, 13). Central stylet about 

 three-fourths as long as basis, rather small, but of typical proportions. 

 Each of the two lateral pouches usually contains two accessory stylets, 

 in size and shape like the central stylet. Basis measures about .o6-.o7 



