14 Catalogue of Chaetopoda 



the principal change being the formation of an order for the family 

 Telethuses. His arrangement may he tabulated thus : — 



I. Anterior extremity of body usually provided with feelers and tentacles ; 



almost all have feet, ajid the gills are external. 



1. Notobranehes. 2. Cephalobranches. ;i. Mesobranches. 



Aphroditees. Serpulees. Telethuses. 



Eunicees. Sabellees. 



Nereidees. Amphitritees. 



Solenicoles.' Oecodontes." 



Amphinomees. 



II. No head or antennae, the majority have no feet, organs of respiration 



internal ; live in fresh water or earth, some ai'e parasites. 



4. Entdrobranches. 

 Maldanies. Lombrieines. Filiformes.'' Hirudinees. 



This classificatiou shows in a striking manner how a too exclusive 

 use of one character, namely the gills, brings together forms which 

 are really not related. For instance, Latreille placed under the 

 Mesobranches, in the family Telethuses, the genera Arenicola and 

 Branchellion, although he remarked that the latter genus appeared 

 to belong to the Hirudinees, but he was so obsessed with the value 

 of the branchiae as a character, that the presence of gill-like out- 

 growths along the middle region of Branchellion outweighed all its 

 other characters. The association of the Maldanies with the earth- 

 worms was another mistake of the same kind. The re-introduction 

 of some Mollusca and of Gordius among the Annelids was also a 

 retrograde step. Altogether, therefore, the classification of Latreille 

 marked no advance in knowledge, but tended to confusion. 



In 1816 Blainville* published a classification of the animal 

 kingdom, in which the seventh and eighth classes of articulate 

 animals were designated respectively Setipodes and Apodes, the former 

 comprising worms with, and the latter worms without chaetae. The 

 class " Apodes " included " Entozoaires " and leeches, which latter 

 were thus separated from the rest of the ringed worms ; this class 

 need not be further considered here. The Setipodes wer(3 divided 

 into three orders, according as the rings of the body were markedly 

 dissimilar, slightly dissimilar or similar. In 1828 Blainville ^ re- 



' For the genus Spio. 



- Contains the genera Dentaliwm and Siliquaria, 

 ^ For the genus Gordius. 



* Bull. Sci. Soc. Philomath., Paris (1816), p. 105. 



•"■ " Vers," in Diet. Sci. Nat., Ivii, Paris (1828). In this later classification 

 the subdivision " Apodes " includes also Sipunculids. 



