286 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



A pair of peculiar vesicles lined with highly columnar epithelium 

 lies in front of the brain and beside the esophagus. Their precise 

 nature and function have not been determined. 



Hlood and nephridial systems. — The cei)haliG blood lacunae 

 conform to the usual type for the genus. The dorsal vessel passes 

 inside the muscular walls of the proboscis sheath at the posterior 

 end of the brain region, and again leaves the rhynchocoel near the 

 anterior end of the intestinal caeca, or some distance behind the 

 nephridiopores. Numerous large blood lacunae lie in the body 

 parenchyma above and external to the lateral nerves in the posterior 

 esophageal region. 



The nephridial tubules extend forward nearly to the brain, and 

 ramify in the parenchyma above the lateral nerves. Their branches 

 are remarkably large and numerous. They extend backw^ard some- 

 what beyond the anterior ends of the intestinal caeca. Near their 

 middle portions a pair of large efferent ducts passes immediately 

 above the lateral nerves and then bends sharply tow^ard the ventral 

 surface. After passing below^ the level of the lateral nerves, these 

 ducts bend farther toward the median line and pass obliquely 

 througli the muscles to open on the ventral surface of the body. 

 The nephridiopores are thus situated even nearer the median line 

 than are the lateral nerves. 



NerDOHs system and sense orr/ans. — Brain is of the usual massive 

 form with neurochord cells and very large dorsal and ventral com- 

 missures. Nerves are also very highly developed. 



The cerebral sense organs are situated beside the brain, and have 

 nearly the same extent as the dorsal ganglia (PI. 24, tig. 181). The 

 short and broad canal on each side opens to the surface on the 

 ventro-lateral margin in the region of the dorsal commissure, while 

 the posterior end of the sense organ lies beside the posterior end of 

 the dorsal ganglion. From the posterior end of this ganglion a 

 large nerve enters the sense organ. 



R&productwe organs. — As stated above, the most anterior sexual 

 glands are situated anterior to the opening of the pylorus into the 

 intestine. The more anterior sexual glands lie external to the lateral 

 nerves, while farther back they lie both external to the nei'ves and 

 nearer the median line. In a specimen collected in July the ova 

 were nearly mature, and large oviducts were formed in the body 

 walls as far as the basement layer. In all the cases observed the 

 oviducts passed toward the ventral surface. 



