200 THE GENERA OF NEMERTEANS. 



name. Hemicyclia , Polystemma, Ommatoplea and Chloraima 

 have again made room for generic names with undisputed 

 claims to priority ; Cnidon was used for a true Cerebratulus 

 as will be shown hereafter , Alardus and Pylidium were 

 only very young stages of a species of Lineidae. The ame- 

 rican genus Cosmocephala was only lately introduced into 

 the European fauna by 0. F. Jensen (Turbellaria ad littor. 

 Norvegiae. Bergen 1878) and applied to a worm which was 

 probably a true Amphiporus. As to Rhamphogordius^ Acicula 

 and Scotia it is very questionable whether the animals 

 described under these names were Nemerteans. 



Akrostomum may possibly apply to a division of armed 

 species ; Baseodiscus was founded on a mutilated specimen 

 of Folia delineata ; Ditactorhochma , Quatrefagea , Ptychodes , 

 Loxorrhoclima ^ Ototyphlonemertes , Otoloxorrhochma and Ave- 

 7iardia were names with which Diesing, Sclimarda and 

 Giard unnecessarily burdened the synonymy of the group. 



The table on page 201 is intended to show at a glance 

 the general conclusions which I have come to respecting 

 the degrees of affinity existing between the different genera. 



Carinella Johnst. must without doubt be regarded as a 

 form which in its structure has retained more primitive 

 characters than any of the others : its central nervous system 

 lies immediately under the skin , its two longitudinal 

 lateral nerves are nowhere found enclosed by the muscular 

 tissue of the body-wall but always exterior to this. This 

 situation of the nerve-tissue which is ontogenetically a pro- 

 duct of the epiblast reveals a more primitive condition. 

 So does the intestine and so does the proboscis. The first 

 is not yet provided with those numerous and regularly 

 placed coeca which in the more developed forms branch 

 off right and left throughout the whole length of the animal , 

 with the exception of the oesophageal region. In Carinella 

 a simple intestinal canal is present in the tail as well as 

 in all the other body regions. The proboscis is thin and 

 slender, only very rarely extruded and provided in its 

 anterior part with urticating organs. A constricted part 



Notes iroxn the Ley den jMusenrri. 



