ALASKA NEMERTEANS 



31 



Somewhat similar bodies may be found in various other Metanemerteans, 

 notably in Amphiporus bimaculatus and A. leuciodus. Here too they 

 appear to originate as secretions in the glandular cells of the epithelium. 



The lateral nerve cords unite above the posterior end of the alimen- 

 tary canal as usual. 



The tissues of the head in front of the brain contain large numbers 

 of sub-muscular glands which open mainly on the anterior extremity, 

 although a portion of them open directly outwards. These sub-mus- 

 cular glands do not extend back into the esophagal region as they do 

 in many other species. 



The intestinal caecum is paired from its origin. Its two branches ex- 

 tend forward on each side of the esophagus until they reach nearly 

 to the brain. Here they bend dorsally (pi. xm, fig. 2) and terminate by 

 abutting closely against the posterior ends of the dorsal brain-lobes. 



The ova are large and opaque. They appeared to be fully mature 

 in June. 



Habitat. This species was found only at Sitka, where it was not 

 uncommon among hydroids, broken shells, etc., in clear water. 



9. ZYGONEMERTES ALBIDA sp 



pi. in, fig. 2 ; pi. viii, fig. 5. 



This is a small, moderately slender spe- 

 cies, very active in habits. It was met with 

 only at Victoria, B. C, on the piles of a 

 wharf. Sexually mature individuals were 

 not more than 25 mm. in length. It was 

 associated with Amphiporus leuciodus, 

 which it somewhat resembles. 



Color. There are no markings on the 

 body, the color being white with a tinge 

 of yellow both above and below. 



Ocelli. This species may be easily rec- 

 ognized from other described forms by the 

 arrangement of the eyes (fig. 6). These 

 are scattered somewhat irregularly on the 

 head in front of the brain, and extend back- 

 ward as a single row on each side along the 

 lateral nerves for about two-fifths the length 

 of the esophagal region. The ocelli on the 

 head are roughly arranged in two irregular 

 rows on each side. There is an outer row 



nov. 



Fig. 6. Zygonemertes al- 

 bida. Outline of anterior 

 portion of body to show 

 arrangement of ocelli, br, 

 brain ; n, lateral nerve ; ps, 

 proboscis sheath. X I2 - 



