408 G. WYNHOFF. 



to each other than the Metanemerteans with either of them. The 

 position of the mouth behind the brain, the structure of the ahmentary 

 canal, the tendency to a complicated structure of the body wall, the 

 development of an outer longitudinal muscle layer, the presence of an 

 inner circular muscle layer of which traces may be found at least in 

 every family, the structure and position of the cerebral organs and the 

 position of the nervous system, which only secondarily migrates through 

 the outer circular muscle layer, together with the absence of any 

 structure in the proboscis, which reminds us of its peculiar complication 

 in the ordo Metanemerteans, are so many points of resemblance, that 

 I do not hesitate to join Palaeonemertini and Heteronemei^tini together 

 in one order, the ordo Anopla of Max Schultze. 



Burger's 31etane.mertini = ^\\hTQc\\i'B Ho2Jlo7iemcrtini constitute my 

 second order, for which Max Schultze's name Enopla ought to be 

 restored. They are characterised by the situation of the mouth in 

 front of the brain, the presence of an oesophageal diverticulum, the 

 structure of the body-wall, the peculiar structure of the proboscis and 

 the presence of stylets, the position of the nervous system in the 

 parenchyma of the body, the situation and structure of the cerebral 

 organs, the uniformly built vascular system. 



Palaeonemertini and Heteronemertini have been reduced to the rank 

 of suborders. The nomenclature of " Das Tierreich " has been adopted. 



As iconographical works I have everywhere referred to : 



1. Bilrger, 0. Die Nemertinen des Golfes von Neapel. Fauna und 

 Flora. Monogr. 22, 1895. 



2. Joubin, L. Les Nemertiens. Faune franqaise par R. Blanchard 

 et J. de Guerne. Paris, 1894. 



3. Mcintosh. A Monograph of British Annelids. Part I. Nemer- 

 teans. Kay Society, London, 1873-1874. 



Ordo I. ANOPLA. 

 In addition to the outer circular and the inner longitudinal muscle 

 layers an outer longitudinal and an inner circular muscle layer 

 may be present. The nervous system is situated in the body wall. 

 Mouth always behind the brain. No diverticulum of the oesophagus. 

 No stylets and no peculiarly built proboscis. 



SuBORDO I. PALAEONEMERTINI. 



Lateral nerves and brain nearly always situated outside the muscular 

 body-wall. The body-wall consists of an epithelium, a circular muscle 

 layer and an inner longitudinal muscle layer ; the inner circular muscle 

 layer may be absent. 



