1903] On the Nemerteans of Norway. 13 



ti. Linens niveus n. sp. 



Localities. Herløfjord on mud bottom from 100 metres. Byfjord 

 (near Ask) on mud from 140 metres. 



Oecurrence. About half a dozen speeimens as the result of about 

 the same number of dredgings, hence fairly common. 



External features. A small species averaging about 30 mm. in 

 length and rather over 1 mm. breadth. Body slender and 

 rounded and of uniform breadth. Colour white with red brain. 

 The mouth is round and small and to its level reach the 

 head slits. In none of the speeimens obtained was a 

 caudicle present. It is therefore probably not present in 

 this species. 



In the body wall the epithelium rests on a very fine basement 

 membrane. It is not very high and contains a number of 

 unicellular glands which stain w ell with picric acid. Of the 

 muscle layers the outer longitudinal is considerably the thick- 

 est, though both the circular and the inner longitudinal layers 

 are well developed in the oesophageal region. Longitudinal 

 fibres may occur between the oesophagus and the proboscis 

 sheath. The cutis glands are well developed in the oesopha- 

 geal region and extend right through the outer longitudinal 

 muscle layer (Pl. I, fig. I). Behind the oesophageal region 

 they are practically absent. Just external to the layer of 

 circular muscles, and separating it from the nervous layer, is 

 a thin though well marked basement membrane. 



The proboscis is three-layered i. e. contains two layers of longitudi- 

 nal separated by a layer of circular fibres. All three layers 

 are very thin. Muscle crosses can just be distinguished. 

 The proboscis sheath extends the hind end. 



The alimentary canal is provided with pouches in the intestinal 

 region. These however are very shallow being not much 

 deeper than half the width of the intestinal lumen. For a 

 short distance behind the oesophagus the intestine is un- 

 provided with pouches. 



The vascular system in the cephalic region shews irregular la- 

 cunae. The lateral blood lacunae in the oesophageal region 

 are large and lie on either side of the proboscis sheath. They 

 send small branches to the wall of the rhynchocoelom resembling 



