^903] On the Nemerteans of Norway. 25 



The proboscis is large, three layered, and contains well developed 

 muscle crosses. The proboscis sheath extends throughout the 

 body. 



Ålimentary mnal. The mouth is large and its anterior border 

 is found at about the level where the cerebral organ ends. 

 The oesophagus is not very long and the intestinal diverticula 

 commence soon after the junction of the oesophagus and 

 intestine. 



The vasa i lar system presents a cephalic lacuna above the rhyn- 

 chodaeum. A little way before the end of the oesophagus 

 the oesophageal network ceases to extend ventral to it. Large 

 lateral lacunae are formed which shortly after become the 

 lateral vessels when the level of the intestine is reached. 

 The dorsal vessel leaves the proboscis sheath at about the level 

 where the excretory system terminates. 



The excretory system commences a little way behind the mouth. 

 The tubules extend ventral to the level of the nervous 

 side stems. Yariability occurs in the number of the ducts. 

 In two small specimens a single pair of ducts only occurred 

 near the posterior end of the system (Pl. II, fig. 21). In a 

 larger specimen 6 ducts occurred on one side and 9 on the 

 other. It is possible, as Oudemans 1 ) has suggested, that the 

 number of ducts increases with the age of the specimen in 

 this species. 



The gonads are first found a little way behind the level where the 

 first intestinal diverticula occur. With these they alternate 

 regularly. 



The nervous system is well developed. The dorsal ganglion is at 

 least double the size of the ventral. The cerebral organ is 

 large and rounded in shape. The buccal nerves form a cir- 

 cum-oesophageal commissure. The head slits are very wide 

 and deep. The depth of each head slit in the brain region 

 is about l U of the total diameter of head. They usually 

 extend backwards a little past the cerebral organ and then 

 terminate fairly abruptly. In a small specimen however they 

 came to an end just before the level of the cerebral organ. 

 Head glands are practically absent. No eyes. Small frontal 

 organ present. 



*) Oudemans, Quart. Journ. Mic. Sc 1885 (Supplement). 



