14 



splierical nuclei (PL III., fig-. 5). It is spaiing-ly provided 

 with long cilia. Xear the blind end of a tnhule these 

 cilia are often more ahnndani, and are directed awav from 

 <h(> hlind end (PL III., fig. 5). Xo flame cells, however, 

 have l»een detected in this species. 



The excietory system lies almost wholly above the 

 level of the lateral nerve cords, never extending into the 

 lacunar network ventrally. Though it is in close con- 

 tact with the (esophageal lacunae, there is no communica- 

 lion between the vascular and excretory systems. 

 Although certain observers claim to have demonstiated 

 such a communication for certain of the more primitive 

 forms, such as Cor/iieJIa and Carinoma, it is exceedingly 

 doubtful whether it exists. Concerning the nature of the 

 fluid contained in the excretory system no observations 

 ha VI' l)een made. 



NERVOtTS SYSTEM. 



The nervous system consists essentially of two longitu- 

 dinal cords extending throughout almost the entire length 

 of the body and dilating anteriorly into the brain. Pos- 

 teriorly they unite by a fine commissure ventral to the 

 rectum. For their Avhole course they lie immediately 

 outside the circular muscle layer, and are conspicuous 

 objects in a transverse section of the worm (PI. III., fig. <S, 

 ,s-.s.). Viewed thus they are seen to be conqjosed of an 

 inner granular-looking portion of a ukuc or less circular 

 outline, surrounded by a layer of ganglion cells. The 

 latter are not present on the side next to the circular 

 muscles, and are very scarce externally. The fibrous core 

 is bounded by a thin connective tissue layer, the inner 

 neurilemma, separating it from the ganglion cells. Out- 

 side the ganglion cells is another connective tissue layer, 

 which has been teiined the outer neurilemma. Tht> inner 



