PLYMOUTH NEMERTEANS. 423 



part of the body, and exists usually in the anterior third only. 

 Neurochords or neurochord cells fail. 



I. Fam. emplectonematidae. 



Mostly very long and flat forms. Proboscis short and rather stout, 

 with one very differently shaped central stylet only. Very often with 

 many small eyes ; seldom two or four eyes. No statocysts. 



Genus Emplectonema. 



Very long and slender. Alimentary tract and proboscis open together. 



Cerebral organs very small, generally situated a long distance in front 



of the brain. Mostly with many small eyes. The proboscis sheath 



does not quite extend to the second third of the body. Sexes separate.. 



1. Emplectonema gracile {Johnst.). (Mcintosh. Monogr., PL II, 

 Fig. 5.) 



Locality : In dredgings from the Mewstone ; between tidemarks at 

 Breakwater, Drake's Island, Cawsand Bay. Far less common than the 

 next species. 



The colour of this Nemertean is usually a more greyish green than 

 the figure in Mcintosh's monograph indicates ; ventral surface white. 

 The head is lined with white and possesses a faint yellow transverse 

 bar. It is broader than the body, but not sharply separated. Cere- 

 bral organs a long distance in front of the brain. 20-30 eyes in two 

 groups at both sides of the head. The handle of the central stylet is 

 twice the length of the stylet itself ; all stylets are curved. With two 

 pouches each containing 5-6 accessory stylets. Length 20 cm. or more, 

 breadth 1 mm. 



Geographical distribution : This species is widely distributed. It is 

 known to occur on the West coast of North America as well as in 

 Chile and the Aleutian Islands, the coasts of France and Germany, 

 Madeira and the Mediterranean. 



2. Emplectonema neesi (Oerst). (Mcintosh. Monogr. PI. Ill, Fig. 6; 

 and Joubin, Les Nemertiens, PI. Ill, Figs. 77-80.) 



Locality : Common between tidemarks in the Sound ; from Break- 

 water and the Mewstone ; occasionally met with in dredgings at a 

 depth of 10-15 fathoms. 



This Xemertean is much more abundant than U. gracile. However, 

 it is not so widely distributed. JE. neesi has been recorded only from 

 the Atlantic coasts of Europe. It ranges from Iceland to the Channel. 



Head broadened and of a yellowish colour, paler than the body. 

 The dorsum has a brown hue in which flesh-coloured stripes occur; 



