COLLECTION OF NEMBRTEANS PROM SINGAPORE. 121 



(2) The excretory ducts generally show a certain amount 

 of expansion in the circular muscle layer^ the gonadial ducts 

 never. 



(3) Spermatozoa may often be detected in the gonadial ducts 

 though not in the excretory ducts. 



(4) The excretory ducts generally pass out just over the 

 side stem^ and take a more or less horizontal course through 

 the body-wall. The gonadial ducts_, on the other hand, are 

 usually given off somewhat more dorsally, and their later 

 course is directed more vertically than is the case with the 

 former (fig. 9). 



Such considerations appear to show conclusively that, 

 although these two sets of ducts co-exist in the same region 

 in this particular worm, there is no connection between them ; 

 moreover, they point to the improbability of any homology 

 being established between the two sets of ducts, whose chief 

 feature in common appears to be that of repetition. 



With regard to the nervous system the brain is small 

 for the size of the animal. The ventral ganglion is small 

 compared with the dorsal (fig. 6). The oesophageal commis- 

 sure is well marked and contains ganglion-cells (fig. 6 a, one.) . 

 The side stems end blindly near the anus without forming a 

 conmaissure above or below the rectum. Possibly this may be 

 owing to injury and subsequent regeneration, but it is impos- 

 sible to say without more material. 



The cerebral organ is small. The gland cells form a 

 peculiar process directed inwards and ventralwards (fig. 6a, 

 gcorg). 



The cerebral canal opens to the exterior laterally and some- 

 what ventrally. 



Eyes are apparently absent, as careful search over sections 

 through the precerebral portion of the groove failed to reveal 

 any structures which might be construed as such. With the 

 exception of E. rugosa (7) all the other species of the genus 

 known possess these sense organs. 



The head glands are well marked (fig. 6, hg.) and stretch 

 back over and under the brain well into the oesophageal region. 



