328 THE NATURAL niSTOEY EEVIEW. 



E. Leuckart* has still further modified the groups of Vogt, 

 which he extends so as to embrace the whole departfcent of Worms, 

 thus : — 



VERMES. 

 Class I. Class II. 



'* Platodes. Nematodes. 



(4 orders.) (4 orders.) 



Turbellaria. Acantliocepliala. 



Cestodes. Nematoidea. 



Trematodes. Chcetognatha . 



Hirudinei. Chcetopoda. 



So far back as 1838, M. Milne Edwardsf established the division 

 of * "Worms/ in its modern or restricted sense, as a province J of the 

 Annulose sub-kingdom. He thus expressed himself:— 



"In a word, I think M. de Blaiuville right in referring the 

 " Helminths to the series of articulate animals, and I am of opinion 

 " that this department should be divided into two principal groups, 

 " the one comprising the Articulata, with jointed appendages, and 

 " the other the Annelids, Helminths, Eotifers, etc., for which series 

 " the common name of worms may be retained." 



M. Milne Edwards has himself subsequently introduced a number 

 of minor changes, affecting the sub-divisions of the group in 

 question. 



Many of the German naturalists, following the example of 

 Siebold, have elevated ' Vermes ' to the rank of a complete sub- 

 kingdom. 



At a later period, M. Milne Edwards§ proposed a binary classifi- 

 cation of the Worms in accordance with the modifications of their 

 nervous system. It has long been known that among the higher 

 worms the principal ganglia, with their commissures, form a double 



* Op. cit. supr., from which we quote. See, however, his ' Bericht,' in Wieg- 

 mann's Archiv. wherein the above arrangement was first announced. 



t Ann. d. Sci. Nat. Zool. Ser. 2. Tome X. p. 194. 



I " Sous-embranchement" — " Grande division." He uses both these words on 

 various occasions, evidently meaning thereby a group less than a sub-kingdom 

 (embranchement), and gi-eater than a class. 



§ In his lectures at the Jardin des Plantes (probably for 1846) as we learn 

 from De Quatrefages, who seems to have been the first to promulgate this 

 arrangement (Voyage en Sicile, p. 206). See also Blanchard, ' Sur L' Organisation 

 des Vers,' (Ibid., Pait UI). 



