Historical 19 



such obviously segmented worms as leeches (Bdellidea) and earth- 

 worms (Scoloces) was indefensible. The wide separation of Toniopteris 

 (Gymnocopa) from its relatives is a further defect of the Table, and 

 there seems no sound reason for the adoption of the term Scoloces 

 for the Oligochaeta of Grube. 



Quatrefages (Hist. nat. des Annelcs, 1865) also restricted the 

 limits of the class Annelides, excluding from it all worms except the 

 Tubicoles and Dorsibranches (Guvier) or Errantes (Audouin and 

 Edwards), so that the class, as he defined it, was equivalent to Grube's 

 order Polychaeta plus the Tomopterids. Quatrefages' classification of 

 Annelids depended primarily on the principle laid down by Blainville, 

 namely, the nature of the segments of the worms. Those Auuelids 

 in whicli the segments of the body are similar to each other, and in 

 which, therefore, the body is not divided into distinct regions, were 

 placed in the order Errantes ; those in which the repetition of parts is 

 sharply interrupted in one or more places, and in which, consequently, 

 the animal is divisible into distinct regions, were placed in the order 

 Sedentaires. These orders M^ere equivalent respectively to the IJapacia 

 and to the Limivora plus Gymnocopa of Grube. The distribution of 

 the families under these two sub-orders is shown below. 



Annelides Eri'antes Annelides Sedentaires 



(A. Erraticae). (A. Sedentariae) . 



Aphroclitiens. Chloremiens. Chetopteriens. Leucodoriens. 



Palmyrions. Nereidiens. Tomopteridiens. Hermcllicns. 



Euniciens. Syllidiens. Clymeniens. Pectin airiens. 



Lombrineriens. Hesioniens. Arenicoliens. Terebelliens. 



Amphiaomiens. Phyllodociens. Opheliens, Serpuliens. 



Nephtydiens. Glyceriens. Ariciens. 



Neriniens. Polyophthalmiens. 



CiiThatulicns. 



Prof. Ehlers ^ admitted that the order Oligochaeta, as defined by 

 Grube, formed a natural assemblage, but was doubtful whether the 

 order Polychaeta could be so regarded. He preferred the system of 

 Savigny, which he praised as embodying the soundest principles. He 

 regarded the three sub-orders Nereideae, Serpuleae and Lumbricinae 

 (the latter, of course, exclusive of the Echiuroidea) as representing 

 three essentially difterent types of Chaetopoda ; but finding that 

 certain genera could not be properly placed in these orders, Prof. 

 Ehlers founded a fourth sub-order, Ariciea, intended to contain 

 genera which had been placed by some authors in the Nereideae and 

 by others in the Serpuleae. Only the sub-order Nereidea was con- 



' Die Borstenwiirmer, Leipzig (1866), pp. 52-57. 



C 2 



