ALASKA NEMERTEANS 79 



on the dorsal side of the lateral blood lacunae, and projecting freely 

 into the cavity of the lacuna. From each coiled tubule an efferent 

 duct leads directly to the dorsal surface of the body. Back of these 

 anterior, isolated nephridia a continuous richly branched and much 

 coiled canal extends posteriorly on each side as far as the end of the 

 esophagal region. The branches of these canals are limited to the 

 dorsal and lateral surfaces of the lateral blood spaces, which occupy 

 the angles between the esophagus and the proboscis sheath. The 

 coiled tubules project freely into the blood spaces, and encroach con- 

 siderably upon their area. The very numerous efferent ducts, which 

 are given off from these tubules, pass directly outwards to the surface 

 of the body. Those which pass out from the most lateral of the ne- 

 phridial tubules, open on the dorsal surface near the lateral margins of 

 the body, while those which leave the tubules nearest to the proboscis 

 sheath open on the dorsal surface not far from the median line. The 

 greater portion of the nephridiopores, however, lie rather nearer to 

 the lateral margins than to the median dorsal line. Although there are 

 practically the same number of efferent ducts on each side, this does 

 not signify that these ducts are paired, but rather that the average 

 number on each side is identical. In several instances an unusually 

 large efferent duct on one side was accompanied by one of similar 

 size nearly opposite. These ducts vary greatly in size, some being 

 several times as large as others. Great irregularity likewise exists as 

 to their distribution along the course of the nephridial canal. In the 

 anterior third of the esophagal region they are well separated, but 

 more posteriorly, portions of two or three sometimes appear on the 

 same side in a single section. 



Sexual glands. — The reproductive glands appear immediately be- 

 hind the nephridia, and in both sexes alternate with the intestinal 

 pouches. The sexual products were fully mature in July, and in both 

 sexes the genital ducts were fully formed. They were lined with a 

 special flattened epithelium, and opened on the dorso-lateral aspects of 

 the body in both sexes. The ova when immature are attached by a 

 narrow stalk to the wall of the ovary, and later break off and fall into 

 the ovarian cavity. The spermatozoa have short, oval heads instead 

 of the slender, pointed ones so common in the genus. 



Habitat. — Yakutat ; under stones at low water ; not common. 



