208 CLASS VI. 



the same time, added to it the Entozoa 1 . Some years afterwards 

 CUVIER discovered that many of these animals have red-coloured 

 blood, and thought that a name implying this was justifiable (vers 

 a sang rouge], whilst LAMARCK, on account of the rings into which 

 their body is divided, named them Annelides. 



It was necessary to premise these historical notices in order to 

 make it clear why we have given to this class of animals the name 

 "Kinged Worms;" and, notwithstanding, include in it animals 

 whose body is not divided into rings. The name may be defended 

 by similar instances from other classes of animals, where names do 

 not always suit all the individuals in them 2 . But, further, we 

 prefer this name to that of " Worms," because this last is too 

 indeterminate, and, as has been alleged above, has a double meaning. 



One of the best writers on the Annulata is 0. F. MUELLER, to 

 whom the whole of Zoology is indebted for distinguished services. 

 The immortal PALLAS, also, -described many ringed worms, and 

 investigated them anatomically. In the present century they have 

 been especially investigated by SAVIGNY, MILNE EDWARDS, GRUBE 

 and OERSTED. EHRENBERG has placed some of these worms, 

 on account of the vibratile cilia with which their integument is 

 beset, in a separate class, under the name Turbdlaria. But, besides 

 that we think too great a multiplicity of classes is to be avoided, 

 some of these Turbellaria approach far too nearly to other natural 

 divisions of the Annulata to allow us to place them in a distinct 

 class of the animal kingdom 3 . 



CUVIER and LAMARCK placed the Annulata higher in the animal 

 kingdom than the rest of the articulates ; above the Crustaceans. It 

 is true that the last-named Zoologist considered the Crustaceans to be 

 the more highly organised, but believing that the Annulata ought to 

 stand above the Insects, and that it was inexpedient to break the con- 

 nected series formed by the Insects, Arachnoids, and Crustaceans, 



1 Tableau element, de VHist. not. des Animaux, 1798, p. 624 ; Le$. d'Anat. com- 

 paree I. ivi&me Tableau. LAMAKCK adopted the same class in his Systeme des Anim. 

 sans vertebres, i8or, p. 315. 



2 The class of the Acalephce for instance, the order of the hemiptera, a name which 

 is properly applicable to the division of the heteroplera alone. 



3 In the following general view of the internal structure of this class we shall 

 especially fix oiir regards on those animals which indicate most clearly the articulate 

 type; for the rest we refer to the special notices in the Systematic Arrangement. 



