496 Howard Edwin Enders. 



These cells bear rather stout cilia at their free ends. The ciliated 

 intestinal groove is not mentioned by any workers. 



Vascular and Nervous Systems. — On the blood system I have 

 confirmed Laffuie's descriptions from transverse sections of adult 

 individuals. A peribuccal vessel communicates both dorsally and 

 ventrally with a straight tube located in the median mesenteries 

 which suspend the esophagus. The ventral vessel is a cylindrical or 

 a flattened tube that extends the entire length of the ventral mesen- 

 tery (Figs. 15-19). I have not observed any transverse branches 

 from the ventral vessel, nor have I studied its posterior communica- 

 tion. The dorsal vessel in the anterior region occupies the dorsal 

 mesentery, but at the posterior border of the anterior region it 

 "spreads out dorsally and laterally and loses its walls." Laffuie 

 claims that the colored fluids injected backward into the dorsal 

 vessel passed out of the vascular space into the body cavity. 



Likewise, I verified only from sections the general arrangement 

 of the central nervous system. It consists essentially of a double 

 ganglionic chain which lies beneath the ventral integuments and 

 between the ventral muscles of the middle and anterior regions (Figs. 

 15-19). Its ganglia, at the level of the segments, are united by deli- 

 cate cross strands of nerve tissue. Each ganglion gives off a series 

 of from four to ten lateral branches that supply the branches of the 

 parapodia and the skin of the same side. The distribution of these 

 lateral nerves was the basis upon which Laffuie so well worked out 

 the homologies of the segTiients. Anterior to the ganglion of the 

 twelfth segment the heretofore parallel nerve cords diverge and extend 

 forward along the lateral margins of the ventral plastron to the base 

 of the ventral lip of the buccal funnel. Here each bends dorsally 

 and backward thence, in the dorsal lip, they join over the median 

 line to complete the dorsal loop, or "cerebral band," and the "esoph- 

 ageal commissure" of other annelids. 



In the anterior region Laffuie says there are no less than eleven 

 pairs of ganglia. They are united mesially by long parallel fibres 

 which cross the plastron, and externally they give off lateral fibres 

 to the nine setigerous segments, to the eyes and to the antennae, and 

 thus represent "at least eleven segments" in the anterior region. 



