20 



E. NOMUBA : 



toward the ventral median line and unite with the first ventral 

 ganglion in segment II, at its anterior corners. 



So far as I have observed, no nerves are given off from the 

 brain into the pharyngeal glands. 



The ventral ganglia are large, lie at the middle of the seg- 

 ments, and give off certain pairs of nerves to the body wall and the 

 visceral organs. The ventral nerve cord is generally deltoid or 

 dorso-ventrally flattened and elliptical in cross section, and in the 

 greater part of the genital segments it is very flattened. It con- 

 tains three longitudinal neural canals (fig. IG). The median canal 

 commences mostly with segment VII, is dorso-median in position 

 and larger in the anterior part of the body than in the posterior. 



The paired lateral canals com- 

 mence always more anteriorly 



Fig. 16. 



Cross sections of ventral nerve cord. 

 A, from anterior, B, from posterior part 

 of the body, x 300. mc— median canal, 

 mm — median muscle bundle, lc — lateral 

 canal, lm — lateral muscle bundle, pt — 

 peritoneum, gc — ganglionic cells. 



than the median, mostly at the 

 middle of segment VI ; thence 

 they run backwards always close 

 to the dorsal border of the cord 

 side by side with the median 

 canal. These lateral canals are 

 small in the anterior segments. 

 but always larger than the median in the posterior segments. Near 

 the end of the body and in the genital segments none of these 

 canals are present. 



Some of the fibres of the parieto -visceral muscles, which 

 originate from the body wall at the beginning of each segment 

 and are attached to the viscera, run backwards in three bundles, 

 one median and two lateral, in the dorsal half of the nerve cord. 

 The median bundle consists of from two to six or more fibres but 

 is not so well developed as in Vermiculus pilosus Goodrich, especially 

 in the extra -ganglionic portions, where only two fibres are mostly 



