1901.] SOME ARCTIC NEMERTEANS. 99 



About 4 large eyes are present on each side just in front of the 

 brain. They are arranged in an irregular horizontal row. The 

 total number of eyes is smaller thau in any other member of the 

 genus \ D. willeyamis coming next with a total of 1 6. 



Eunemertes neesi ((Ersted, 1844). 



Nemertes neesi, Mcintosh, 1873-74. 



Emiemertes neesi. Burger, 1895. 



Fragments of a large specimen from Greenland, amounting to 

 35 cm. in length with a breadth of 7 mm. I have compared a 

 series of sections from this animal with a similar series from a 

 specimen of E. neesi procured at Plymouth. The Greenland speci- 

 men is typical both with regard to external colour and form and 

 also internal auatomy. 



Heteron'emertini. 



Cerebratultjs greeni/A^dicus, n. sp. (Plate VI. figs. 1-3 and 

 Plate YII. figs. 10, 12.) 



Portions of two specimens from Greenland and from North Green- 

 land (collected by Herr Lohmann). The anterior end was preserved 

 in each case. The fragments from Greenland amounted to about 

 8 cm. in length and 7 mm. in width. The fragments from N. 

 Greenland belonged to a larger specimen and amounted to 44 cm. 

 in length and S mm. in breadth. The worms were of a pale dirty 

 brown hue, all traces of the original coloration having probably 

 been extracted by a 10 years' sojourn in alcohol. The head-slits do 

 not extend so far as the mouth, which is very evident as a round 

 hole. 



The epithelium is fairly high and contains a few unicellular 

 glands (Plate VII. fig. 12). It rests upon a fine basement-mem- 

 brane, beneath which is the delicate circular muscle-layer of the 

 cutis. The connective tissue is fairly well developed in the cutis. 

 Its more superficial portion contains small scattered bundles of 

 longitudinal muscle-fibres (Plate VII. fig. 12, mlc). Beneath these 

 are the cutis-glands, which rest directly upon the outer longitudinal 

 muscle-layer of the body-wall. 



In the oesophageal region the outer muscle-layer is about 2| times 

 as thick as the circular layer. The last-named layer is of the same 

 thickness as the inner longitudinal layer. The three muscle- 

 layers preserve approximately the same proportions in the intestinal 

 region. There is no well-marked layer of horizontal muscles over 

 the mouth. No diagonal muscle-layer. 



The vascular system in the head-region pivsenls some slight 



points of divergence from thai usually found in the Lineide. In 

 front of the brain their is a Bingle lacuna which is not divided up 

 by muscle-strands (Plate VII. fig. L0, cfe.). It possesses a longi- 

 tudinal muscle-coat which, together with the rhynchodaeum, is 



1 Punnett : Willey'a Zoological Resulte, pt. v. p. 571. 



7* 



