EECENT WOEKS OS THE ENTOZOA. 325 



The class Vermes of Linneus contained, as our readers know, all 

 those invertebrate* animals which he excluded from his Insects, that 

 is, from the Arthropoda, The 'Worms' of modern systematists 

 constitute a less extensive, though still far from inconsiderable, series, 

 including : — 



a. — The typical Annelids,t or FolycJicsta of G-rube. 



b. — The Earthworms, Naids, and their allies ; Oligochcsta of 



Grrube. 

 c. — The Leeches. 



d. — The GepJiyrea^ or Sipunculoid worms. 

 €. — The jRotifera, or Wheel-animalcules. 

 f. — The Turhellaria^ or Ciliated worms. 

 g. — The Helminths proper, or parasitic worms. 

 h. — The genus Sagittaj and other genera of doubtful affinity ; 

 especially PeripatuSy Tomopterisy and Phoronis.% 

 From the Motif era we here exclude the Ichthydina of Ehrenberg, 

 and from the Helminths, the Pentastomata of Eudolphi (= Acantho- 

 tlieca, Diesing), which appear to be indubitable Arthropod animals 

 of degraded structure. 



Burmeister, Van Beneden, and Agassiz would associate all, 

 or nearly all, the above forms under a single * class,' in the tech- 

 nical sense of that term. This, however, is but a return to the 

 antiquated views of Bruguieres and Oken, which Cuvier long since 

 condemned. 



We believe, with the great majority of modern helminthologiats, 

 that several distinct ' classes' of Worms exist. But it is by no means 

 an easy task to determine the limits of these, and the various forms 

 comprehended under each. Our knowledge of the structure of 

 Worms is still very far from perfect. Nor do naturalists in general 

 possess an accurate acquaintance with the facts already known. We 

 find that scarcely any two of them agree as to what are the primary 

 sub-divisions which this department of the animal kingdom includes. 

 In the preceding list we have endeavoured to enumerate the 



* Besides Limax lanceolatus of Pallas {=Amphioxus) and Myxine. 



f That is, the marine, unisexual Setigera hrancliiata, or " Annelides propre- 

 ment dites" of M. Milne Edwai-ds ( 1 846). 



X Tomopteris would seem to be a Rapacious Annelid (see Grube) of free- 

 swimming habit, reduced to the utmost simplicity of organisation, just as that 

 curious polyzooid form Fharoiiis is, perhaps, but an humble ally of the Tubicolce. 

 Grube places Tomopteris in a special order {Gynviocopa). 



