NEMERTEANS 183 



The posterior esophageal cavity — 'stomach,' or gastric portion of 

 esophagus, as it may be called — is by no means a structure peculiar 

 to the species at hand, for indications of a specialized posterior portion 

 have often been described for the esophagus of other species. Yet in 

 no other Ileteronemertean has this chamber been found to be so highly 

 differentiated. The transition is usually far more gradual, especially 

 betw^een the stomach and the intestine, as is the case in Zygcufolia. 

 The general nature of the cavity resembles the intestinal cascum of 

 the Hoplonemerteans far more than it does the so-called 'stomach* 

 (Magendarm) of these forms. 



Blood and Nephridial Systems. — Cephalic blood lacunae, lateral 

 vessels, and anastomosing blood spaces about esophagus as in related 

 species. Rhynchoccel vessel short, leaving the cavity of the proboscis 

 sheath in the immediate vicinity of the nephridioporcs, or at about 

 one-fifth the distance from mouth to intestinal region. 



Nephridial system remarkably short, but with rather large branches. 

 It commences anteriorly a short distance behind the mouth and is 

 limited to the anterior fifth of the esophageal region. The main longi- 

 tudinal canal on each side is situated as usual in the angle between the 

 proboscis sheath and the esophagus, and the branches ramify about the 

 esophageal blood spaces. After an extent of less than one-fifth the 

 length of the esophageal region, each of the two longitudinal canals 

 swells out into a comparatively large chamber from which the rather 

 large efferent duct passes above the lateral nerve to the nephridioporcs, 

 situated as usual on the dorso-lateral surface of the body. The nephrid- 

 ial canals do not extend farther posteriorly than the position of the 

 nephridioporcs, which are strictly paired. 



Nervous System and Sense Organs. — These structures present no 

 noteworthy peculi-irities. Terminal, or frontal, sense organs appar- 

 ently wanting. Cerebral sense organs well developed and closely 

 united with posterior surfaces of dorsal ganglia. The canal by which 

 each of the sense organs communicates with the posterior end of the 

 corresponding cephalic furrow is broad and short. 



Reproductive Organs. — No sexual products are present in speci- 

 mens collected in August and September. 



Habitat. — A few specimens of this beautifully colored species 

 were found on piles in San Pedro Harbor, Calif. A single specimen 

 was found by Ivlrs. Cockcrell on a kelp 'hold-fast' outside the same 

 harbor. The species also occurs sparingly on the piles at ^Monterey, 

 Calif. 



