ENTOZOA. 



cation wHch, in some important details, will be found to depart 

 from the plans generally in vogue : — 



f Turbellaria 



SlERELMINTHA ) (Ord. 1). 



(Sub-class I.) i Trematoda 



\ (Ord. 2). 



HELMINTHA ) Ccelelmintha NematoAa 



(Class.) ) (Sub-class II.) (Ord. 3). 



Acanthocephala 

 Anbntekelmintha ) (Ord. 4). 



Bntozoa. 



(Sub-class III.) I Oestoda 



(Ord. 6). 



In this scheme it will be noticed that I have not hesitated, on 

 the one hand, to place the Turbellaria amongst the solid or paren- 

 chymatous helminths (sterelmintha, Owen ; a-repea — eXfiivOe?^ ; whilst, 

 on the other hand, I have formed a new sub-class for those hel- 

 minths which are not provided with an intestinal canal (anenterel- 

 mintha ; a — evrepov — eXyttw^fe).* The hollow or cavitary group stands 

 as before {ccelelmintha, Owen; koCKt] — ekfuvdet;). In regard to the 

 first change here proposed, I may remark that the Turbellaria come 

 nearer to the Trematoda than they do to the suctorial annehds ; 

 which latter, be it remembered, are furnished with a complete 

 intestinal tube and anus, and, moreover, their characters, by the 

 intervention of the planarige, are too closely linked on to the Tre- 

 matoda to permit of their being elevated by themselves into a 

 separate class. Von Siebold, however, has done this, in my opinion, 

 on insufficient grounds ; but it is not unlikely that he would, in 

 opposition to the views here advanced, urge the impropriety of 

 calling the Turbellaria true helminths. In reply, I should be ready 

 to admit that the Turbellaria are not helminths in the same sense as 

 the entozoa, properly so called, but by imparting to the term hel- 

 minth a wider signification than that to which it was restricted 



* Since the above was written, Prof. Leuckart (on stowing him the M.S.) dr^w 

 my attention to the circumstance that he had some years back employed the term 

 Anenterata to include the Acanthocephala and Cestoda. He referred me to Carua 

 {System der Thierischen Murphologie, s. 417), where I find the term in question 

 adopted. -T. S. 0. 



