S32 THE NATURAL HISTORY BET3EW. 



prejudices arising from an attachment to particular systems, on tlie 

 one hand, and a desire for innovation, on the other. 



In the foregoing summary of our opinions touching the mutual 

 relations of "Worms, we regret that, for want of space, we have been 

 unable to take up the detailed consideration of the several organic 

 systems of this most interesting and extensive group, more especially 

 of that complex series of parts which may collectively be denominated 

 their * pseudo-vascular'* system. Such a resume ought rightly to 

 precede any exact discussion of the affinities, limits, and sub- divisions 

 of the group in question. We regret, consequently, that we have 

 thus been compelled to present the general results to which our 

 reflections have led us, apart from a full statement of our views of the 

 facts on which these results have been based. But we are not the 

 less confident of the proofs to which we refer, or the less ready to 

 bring them forward, whenever a fitting opportunity ofiers : always, 

 nevertheless, with this restriction, that we profess not to go beyond 

 the present state of science, though ever ready to alter our views as 

 soon as confirmation succeeds discovery. 



{See table, next pctge^ 



We thus see that all the annuloid parasites belong to one class, 

 — Scolecida. This class includes the Turhellana, beside the Entozoa 

 of Eudolphi. 



The Turbellaria need not now detain us. This order includes two 

 sections ; the Froctucha, which are unisexual, and have an alimen- 

 tary canal furnished with botli oral and anal orifices, and the Aprocta, 

 which, in their general hermaphroditism, and the structure of their 

 digestive apparatus, clearly approach the Trematoda. 



Tlie Entozoa, or Helminthsf proper, were divided by Eudolphi 

 into five orders : — Nernatoidea, Acantliocephala, Trematoda, Cestoidea, 

 and Gystica.% These groups have been universally admitted. Siebold 



* Including the ciliated and non-ciliated * water vesssels,' the pseudo-hcemal 

 system, the arabulacral system of the Echiuoderms, and the ' secretory' tubules of 

 various Annelida. 



•f The name Helminths, or rather its Greek equivalent, Qi\[nvq) may be traced 

 as far back as the writings of Hippocrates. Aristotle, in the fifth book of his History 

 of Animals, (Ed. Bekker, vol. i. p. 5.51,) refers to worms which live in the viscera, 

 as those which are called sXjxivGeg (pi. of eXfiig). Of these he distinguishes three 

 kinds, — TrXaTslai, (rrpoyyvXai, and dcncapideg. The word Helminth afterwards came 

 to signify worms in general ; but it was restored to its older signification before the 

 close of the last century. Hermann (Helminthologische Bemerkungen, 1 782-4) is 

 usually cited as the founder of the group Helminthes of modern zoologists. 



X ' Entozoorum Hist. Nat.' and ' Synopsis Entozoorum.' 



