COE: NEMERTEANS OF WEST AND NORTHWEST COASTS. 269 



Alimentary canal. — Esophageal canal extends from very near 

 tip of snout far beyond the most anterior genital glands before 

 opening into dorsal wall of intestine. Its epithelial lining, however, 

 exhibits the usual diffei'entiation characteristic of the stomach and 

 pylorus posterior to the anterior third. No esophageal caecum is 

 developed. 



A broad intestinal caecum extends forward beneath the pylorus 

 about as far as the posterior ends of the nephridia, and somewhat in 

 front of the most anterior genital glands. It sends off the usual 

 short diverticxala above the lateral nerves. 



Blood vessels. — Cephalic lacunae as in related species ; lateral 

 vessels branch considerably and lie closely beside corresponding 

 nephridial tubules, as noted below. Rhynchocoel vessel passes 

 obliquely through wall of proboscis sheath in the vicinity of the 

 nephridiopores. 



Nephridia. — The nephridial tubules extend forward to the brain 

 region, where they are sometimes coiled and twisted about the pos- 

 terior ends of the cerebral sense organs. In one specimen they 

 appear almost as if they were a part of the sense organ itself. 

 Behind the sense organs they become entwined about the lateral 

 blood vessel and its branches. Together they form a crowded mass 

 of tubules, from which the single efferent duct on each side passes 

 to the dorsal side of the lateral nerve, and then makes a sharp bend 

 ventrally to open on the ventro -lateral surface of the body as usual. 

 The nephridial tubules continue but a short distance behind the 

 nephridiopores. 



Nerves and sense organs. — Cerebral ganglia very large, but with 

 the usual structure. 



Cerebral sense organs remarkably large and highly specialized. 

 They lie beside and behind the brain and in the angle between 

 dorsal and ventral ganglia. They open to the ventro-lateral sur- 

 faces of the head by means of broad canals lined with columnar, 

 ciliated epithelium. Posteriorly they become closely connected with 

 the dorsal ganglia from the posterior extremities of which they each 

 receive a large core of fine nerve fibers. Posterior to the termi- 

 nation of the dorsal ganglia the sense organs increase greatly in 

 size by an enormous development of their gland cells. The ciliated, 

 sensory portion of the canal of the sense organ lies farther forward, 

 so that behind the ganglia there is only a large mass of glands 



