COE: NEMERTEANS OF WEST AND NORTHWEST COASTS. 277 



The number of proboscidial nerves (14) will distinguish the pres- 

 ent species from A. arcticus, with 10 such nerves, and A. marmora- 

 ttis, with 16, both of which forms also possess an esophageal caecum. 

 Its relationship to A. occidentalis is noted above. The only other 

 known species of the genus with such a diverticulum to the esopha- 

 gus is A. biniaculatus, and this can be easily distinguished by the 

 presence of two conspicuous black spots on the head. 



69. Amphiporus flavescens, sp. nov. 



PI. 2, fig. 22 ; PI. 16, figs. 97, 98 ; PI. 23, figs. 162-171. 



Body of moderate proportions for genus, rather small, head 

 slightly broader than body in some stages of contraction. 



Size. — Length usually 12 to 20 mm.; width 0.5 to 1 mm. Some 

 specimens obtained were no more than 6 to 8 mm. in length, w^hile a 

 few larger individuals were 25 mm. or more. 



Color. — Very variable, usually wliitish, pale flesh color, or pale 

 yellow (PI. 2, fig. 22). Some individuals are opaque wliite with 

 pale yellow intestinal lobes ; others are translucent, whitish or pale 

 ocher anteriorly, fading to whitish toward posterior end of body ; 

 still others shade from pale orange to ocher, wdth orange intestinal 

 lobes. Females with ripe ova incline to yellow, while males are 

 more of a grayish white ; head and anterior esophageal region of 

 both sexes are commonly flesh colored or pale orange. Brain usually 

 yellowish, intestinal lobes of all shades of pale yellow, gray, and 

 pale brown. Color quickly lost after preservation. 



Ocelli. — Number and arrangement of ocelli present considerable 

 variation according not only to size of Avorm, but to individual pecul- 

 iarities (PI. 16, fig. 97 ; PI. 23, figs. 162-163). There are commonly 

 from 12 to 25 ocelli on each side of head, and these are arranged in 

 two groups on each side. The anterior groixps lie on the antero- 

 lateral margins, and these ocelli-are often arranged in a single irreg- 

 ular row of 6 to 12 on each side. The posterior groups are still 

 more irregularly arranged, and extend from the internal border of 

 posterior ends of anterior groups backward to about the anterior 

 border of the brain. The cluster of 6 to 12 ocelli in each of these 

 groups usiially appears to extend laterally as well as backward (PI. 

 16, fig. 97), but by the increase in the number of the ocelli and the 



