coe: nemerteans of west and northwest coasts. 25 T 



narrow rectum. Near the posterior opening of the rectum prac- 

 tically all the muscles are circular, and this insures a well developed 

 sphincter. A similarly thick circular miiscle is described for a cor- 

 responding region in Taeniosoma punnetti (p. 13). 



A section near the posterior opening of the rectum (PL 21, fig. 

 133) shows how very thick is the integument as compared with the 

 other tissues, and especially with the minvite lumen of the rectum. 



Cephalic glands are voluminous (PI. 21, fig. 131). 



Stihinuscular glands are abundant along the lateral borders of the 

 head in the brain region, but do not continue far back into the 

 esophageal region. 



Alimentary canal. — The rhynchodaeum opens subterminally ;: 

 esophagus soon separates fi'om proboscis sheath, and stomach is 

 unusually small. A broad intestinal caecum lying beneath the 

 pylorus reaches far forward into the esophageal region, as in other 

 species of the genus, while just back of the nephridia, and occupying 

 the same relative position, lies a pair of lateral diverticula of this 

 caecum. Back of the point of origin of this anterior pair of diver- 

 ticula similar lateral lobes are given off from the caecum at fairly 

 regular intervals back as far as its origin from the intestine proper, 

 where they are replaced by the corresponding intestinal pouches. 

 The pylorus becomes of very small diameter toward its posterior 

 end and opens into the dorsal wall of the intestine as usual. 



The rectum is of small size, without lobes, and is provided with 

 a peculiar circular muscular layer, as described above (p. 256). 



Nephridia. — In extent and profusion of bi-anches the nephridial 

 system is remarkable. From near the brain (PI. 21, fig. 131) a com- 

 plex series of branching tubules extends back about one half the 

 length of the esophageal region. The tubules lie imbedded in the 

 body parenchyma just internal to the lateral nerves, and extend 

 some little distance both dorsally and ventrally. In cross section 

 they cover an area several times as great as that of the lateral 

 nerve. The tubules lie in close contact with the walls of the lateral 

 blood vessels, which seem to be imbedded in the nephridial mass. 

 There is a single pair of large efferent ducts. 



Blood system much as in other species of the genus. Median 

 vessel projects freely into cavity of proboscis sheath for some little 

 distance back of the brain, and then lies beneath the sheath through- 

 out the rest of the body. The union of the three longitudinal ves- 

 sels near the posterior end of the body has been described above. 



