984 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
angle between stomach and proboscis sheath. In the intestinal region the lateral vessels lie beneath 
the intestine about halfway between the median line of body and the lateral border of intestine. The 
dorsal vessel occupies a position within the cavity of the rhynchoccel for only a very short distance 
immediately behind the brain. In the mouth region it passes through the proboscis sheath and 
becomes situated immediately ventral to the sheath throughout the length of the latter. At the poste- 
rior end of the proboscis sheath, in the anterior portion of the intestinal region, the dorsal vessel con. 
tinues in the mid-dorsal lihe above the intestine to the posterior end of the body. Throughout the 
length of the intestinal region the dorsal vessel has frequent (metameric ?) anastomoses with the 
lateral vessels. 
Nephridia . — The nephridial canals are remarkable in that they have numerous efferent ducts which 
open into the lumen of the esophagus (figs. 6, 7, nd), as well as others which open on the external 
surface of the body. This remarkable condition is known in but one other species of nemertean, which 
also belongs to the genus Tseniosoma. This is T. melanogrammum (Punnett), a new name proposed for 
Fig. 6.— Tseniosoma cingulalum. Portion of transverse section of body through esophageal 
region, showing arrangement of blood lacunie {el ) , nephridial canals (nep), and nephri- 
dial duct ( nd ) opening through esophageal epithelium (eep) into lumen of esophagus 
(e); ( plm and pcm) longitudinal and circular muscles of proboscis sheath; (In) lateral 
nerve. Other reference letters as in fig. 1. x 90. 
T. quinquelineatum (Quoy et Gaimard). In this species Punnett ® has found in each of two specimens 
sectioned a number of efferent nephridial ducts opening directly through the esophageal epithelium 
into the lumen of the esophagus, in addition to a somewhat smaller number opening above the lateral 
nerves to the dorso-lateral surface of the body. The ducts opening externally are interspersed irregu- 
larly between those opening into the esophagus. Exactly similar conditions prevail in T. cingulatum, 
as stated above. 
The nephridial tubules are profusely branched and rather extensive, being found throughout the 
posterior three-fifths of the esophageal region. The branches are themselves of rather large size and 
are situated on the lateral walls of the esophageal blood lacunae (figs. 6, 7) and in close contact with 
the epithelial lining of the blood spaces. The efferent ducts which open into the esophagus are con- 
spicuous in many instances and show a distinct, though thin- walled, tube (figs. 6, 7, nd) passing 
directly from one of the larger nephridial canals (nep) to the surface of the ciliated epithelium lining 
the esophagus. The efferent duct itself is lined with flattened cells and often presents a distinct lumen 
throughout its length, so that there is not the slightest doubt of the communication between the 
nephridial canals and the lumen of the esophagus. 
a Quart. Joum. Micr. Sei., vol. 44, 1900, p. 116. 
