NEMERTEANS 



Cephalic glands form a voluminous and well-marked mass of deeply 

 staining glands which extends back both dorsally and ventrally nearly 

 to the brain. Their secretions are discharged anteriorly at the tip of 

 the snout as in the Taeniosomidae. 



Alimentary Canal. The esophageal region is remarkably short in 

 comparison with the total length of the body There is a very short 

 esophagus lined with the characteristic glandular and ciliated cells. 

 At the posterior end of this is a decided constriction, or sphincter, 

 which opens into a widened posterior chamber without lateral pouches, 

 but having a lining of epithelium not widely different from that of 

 the intestine. This posterior cavity is even shorter than the esophagus 

 proper, and gradually passes into the true intestine with its paired 

 lateral pouches. The esophagus proper is sometimes only as long as 

 the transverse diameter of the body, and hence, much shorter than in 

 most related species. The cavity behind this evidently corresponds to 

 the ' stomach,' as described by Miss Thompson ( I9O2) 1 for Zygeupolia^ 

 and is doubtless homologous with the posterior esophageal cavity of 

 Lineus rubescens and L. Jlavescens, as described above. In these 

 latter species, however, the epithelial lining of this cavity is markedly 

 different from that of either the esophagus or intestine, while in L. 

 pictifrons, as in Zygeupolia, it resembles the intestinal epithelium 

 very closely. 



Although the change from esophagus to ' stomach ' is very abrupt 

 both anatomically and histologically, yet it is quite impossible to deter- 

 mine exactly where the stomach ends and the intestine proper begins. 

 The anterior intestinal pouches are but slightly indicated and pass 

 gradually into the wavy outlines of the stomach, and the histological 

 features show a similar gradation. The cells of the axial cavity of the 

 intestine retain the appearance of the stomach cells for some distance 

 posteriorly as in Zygeupolia. 



An internal circular muscular layer, such as is described above for 

 L. rubescens and L. jla-vescens just anterior to the intestine, is not 

 found in the present species. 



Blood and Nephridial Systems. There is the usual arrangement 

 of cephalic blood lacunae, lateral lacunaa, rhynchocoel vessel, etc. 

 Branches of the lateral lacunae surround the esophagus, and are gath- 

 ered into a single pair of vessels in the region of the stomach. In this 

 region there are five large vessels in a transverse section of the body 

 the rhynchoccel vessel, the pair of lateral lacunae situated in the angle 

 between stomach and proboscis sheath, and the pair of ventral vessels 



1 Proc. Acad. Nat. Sci. Philadelphia, 1901, p. 709. 



