276 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



A. occidentalism where the diverticula of the intestinal caecum 

 extend far in front of posterior end of esophageal caecum. They 

 are mostly narrow and much branched, and extend dorsal ly above 

 lateral nerves as usual. 



Comparative lengths of various portions of alimentary canal in 

 one individual are as follows : — 

 Posterior border of dorsal ganglia to posterior end of 



opening of esophagus into stomach ... 29 sections. 

 From this point to end of esophageal caecum . . 24 " 

 From end of esophageal caecum to end of pylorus 73 " 



Making length of stomach and pylorus . . . 97 " 



The sections in this instance were .015 mm. in thickness. 



The intestine (mid gut) posteriorly has a comparatively narrow 

 lumen with peculiarly slender diverticula, separated from each other 

 and from the body walls by a very large amount of parenchyma. 



Nepliridia. — Nephridial tubules extend forward to brain region, 

 and are limited to the anterior portion of the esophageal region, A 

 single pair of large efferent ducts passes to ventro-lateral surfaces of 

 body as usual. In each of two specimens sectioned a diverticulum 

 of each efferent duct extended for about a dozen sections posteriorly 

 in the longitudinal muscular layer. 



Cerebral sense organs. — These are remarkably highly developed 

 and are situated beside and behind the dorsal ganglia. The canal 

 connecting each with the exterior passes forward beside the dorsal 

 brain lobes, and thence in front of brain to open into distinct lateral 

 furrows well anterior to brain region. The sense organs reach their 

 maximum development immediately behind dorsal ganglia, and are 

 here but a trifle smaller than the latter. 



The lateral blood lacunae lie immediately behind and beside the 

 sense organs, but do not surround them. A section through the 

 sense organs somewhat resembles superficially a similar section 

 through a Heteronemertean. 



Habitat. — Piles of wharf, San Diego, California ; dredged in 20 

 to 50 fnis. off' San Pedro, California. Not uncommon. 



This species is evidently closely related with A. occidentalis (p. 

 271) which has been dredged oft" Washington, but differs in having a 

 great development of the body parenchyma, in the comparative 

 length of the intestinal caeca, and will probably be found to exhibit 

 differences in structure and armature of proboscis. 



