1903] On the Nemertéans of Norway. ' 21 



The cerebral organ is well developed. The median dorsal 

 nerve is not very conspicous. 



The head slits are fair ly deep, each being about Vs of the 

 total trans verse diameter of the head in the brain region. 

 They end abruptly after the ciliated canal is given off. A 

 large frontal organ is present and the head glands are fairly 

 well marked. 



As regards its general organization M. varicolor shews 

 considerable resemblance to Linens gesserensis. It resembles 

 this species in the structure of the body wall, in the struc- 

 ture of the proboscis and the relations of the sheath of that 

 organ, in the structure and relations of the excretory system, 

 and also of the oesophagus and intestine. The eyes again 

 are similar in position and number. The remarkable colour 

 variations shewn by this species are also paralleled by L. 

 generensis. Almost the only structural differences which se- 

 parate the two species are the presence of a cephalic head 

 loop in L. gesserensis and theabsence of a caudicle. Under the 

 system of classification at present in vogue these two species 

 must in spite of their very close resemblances be relegated 

 to different genera, and M. varicolor takes its place among 

 species with which it has far less in common than it has with 

 L. gesserensis. 



12. Micrura atra n. sp. 



Locality. Alverstrom (near Bergen) from a depth of 80 metres on 

 a bottom of shell sand. A single specimen only was procured. 



Extemal features. A. somewhat flattened form measuring about 15 

 cm. in length with an average breadth of 4 — 5 mm. Colour 

 dark gray above, lighter on the ventral sur face. Head a 

 very deep grey, almost black. The grey of the dorsal surface 

 was suffused with an exquisite peach-coloured bloom. The 

 edges of the head slits and mouth, and the caudicle were 

 pure white. The mouth was large when the worm vas living. 



Body wall. The epithelium is packed with unicellullar glands and 

 rests on a fine basement membrane. Beneath this come a few 

 circular muscle fibrils. The cutis glands are somewhat scanty 

 and the thickness of the cutis is not greater than that of the 



