160 THE NEMERTINI 



the genera Planaria, or Fasciola, or Gordius. And even when the anatomy 

 of the group was better understood, they were retained as members of 

 that class, though various positions were assigned to them within it. 

 Thus, Ehrenberg placed them in his order Rhabdocoela ; Quatrefages 

 created an order Miocoela, which he placed side by side with the Rhabdo- 

 coela and Dendrocoela ; Max Schultze divided the Turbellaria into () 

 Proctucha, to include the Nemertines, which he termed Rhynchocoela ; 

 and (6) Aprocta, for the Turbellaria, s.s. And even in recent times 

 this position has not been entirely given up, for Hatschek, in his Text- 

 book, places the Nemertines in his group Autoscolecida, with the Platy- 

 helmia, Rotifera, Nematoda, etc., all agreeing in the structure of the 

 excretory organs. 



On the other hand, some zoologists have exaggerated the resemblances 

 to the Annelids which the Nemertines undoubtedly bear, and place them 

 in this class (v. Siebold, Leuckart, M'Intosh). Lang includes them 

 in his "Vermes," by which he understands the Annelids, Gephyrea, 

 Polyzoa, Brachiopoda, Nematoda. The more recent authorities who 

 have worked upon the group (Hubrecht, Burger) raise the Nemertines 

 to an independent position between the Platyhelmia and the Annelida : 

 a view that was first taken by Cuvier, who formed the groups "Vers 

 cavitaires" for the Nemertines, in opposition to the "Vers parenchy- 

 inateux " (Platyhelmia) ; later, Blanchard invented the term Aplocoela, 

 and Oersted followed in the same line. The interesting speculations 

 of Hubrecht may here be referred to, viz. the suggestion that in the 

 Nemertine various organs of the Chordata are represented, or are even 

 anticipated in a humble fashion. 



Amongst those who have added materially to our knowledge of 

 genera and species reference may be made to the following : 0. F. 

 Miiller, Oersted (34), Johnston, Keferstein (23), Stimpson, M'Intosh, 

 Hubrecht, Joubin, and Burger; while Duplessis (13) and Guerne 

 worked upon fluviatile species ; Semper and Dendy (10) on terrestrial 

 forms. 



As contributors to our knowledge of the general anatomy of the class, 

 the following deserve mention : Quatrefages (36), Frey and Leuckart (14), 

 Max Schultze (39), Keferstein. But all earlier writers are eclipsed by 

 the brilliant monograph by M'Intosh (27), wherein he gives a critical 

 account of all the earlier work on the subject. Since that time Hubrecht 

 and Burger have, by more modern methods of research, built up on this 

 foundation a magnificent superstructure, culminating in the elaborate 

 memoir by Burger, published in the series of monographs of the Fauna 

 and Flora of the Bay of Naples. 



With regard to special points of anatomy, it is interesting to note 

 that the eversibility of the proboscis was first noted by Da vies (1815) on 

 the addition of alcohol to water in which a Nemertine was living. 

 Johnston was the first to recognise that in some Nemertines the proboscis 

 is provided with a stylet, which is absent in others. But it was a long 

 time before this proboscis and its sheath were properly understood ; for 

 by most of the earlier writers it was regarded as the intestine (Duges, 

 Ehrenberg, Quatrefages), while Oersted described it as a male copulatory 



