Historical 1 7 



dioiques," in which he placed " Annelides," and " Vers monoiques," 

 which included Lombrines, Hirudinees, 1 Turbellaries and Cestoides. 

 The separation of the earthworms from the rest of the Annelids was 

 unwarrantable and was not followed to any extent by subsequent 

 writers. 



Grube's masterly paper 2 on the classification of Annelids appeared 

 in 1850. To him we owe the accurate delimitation of the order 

 Oligochaeta ; this he defined so as to exclude such worms as Cirra- 

 tulus, Troplionia, Travisia and some Gephyrea, which, by previous 

 systematists, had been placed in close association with Lumbrieus. 

 As a result of his admirable studies on the external features and 

 internal structure of Annelids, and of the critical acumen which he 

 brought to bear on the problem, Grube was enabled to define the 

 limits of this order practically as they stand to-day. He introduced 

 the useful names PoJychaeta and Oligochaeta, now universally used 

 and recognised, especially the latter, as designating natural assem- 

 blages of worms. Grube's work ranks, with that of Cuvier and 

 Savigny, as one of the great classics on this subject, and was 

 undoubtedly the most important work on the general classification 

 of Annelids published during the seventy years subsequent to the 

 appearance of Savigny 's monograph. After giving a detailed account 

 of the structures which he proposed to use in the classification of 

 Annelids, Grube arranged these worms in five orders, which he 

 defined thus : 



I. Appendiculata Polychaeta Annelids which, besides having 

 lateral bundles of bristles, bear on the dorsuni or on the head region 

 either lappets, filaments or compound structures ; the bristles are 

 at least eight, and usually many more, in each segment ; these animals 

 live in the sea and, as far as is known, are of separate sexes. This 

 order corresponds to the orders Nereideae and Serpuleae of Savigny. 



IT. Gymnocopa, an order founded to contain the single genus 

 Tomopteris. 



III. Onychophora for the genus Peripatus, which, since the time 

 of Audouin and Edwards, had been considered to be an Annelid. 



1 A considerable number of authors associated the leeches with the flat- 

 worms; for instance, van Beneden (1850, 1852-54), Burmeister (1856), Haeckel 

 (1866), Schmarda (1871), 0. Schmidt (1872), and Vogt and Yung (1888). But 

 the studies of the development of leeches, especially of their mesoblast 

 (Rathke, 1862), showed that they exhibit the fundamental characters of 

 Annelids, and they were so regarded in the text-books of Gegenbaur, Glaus 

 and Huxley. 



2 Arch, f, Naturg., xvi Jahrg., i, p. 249. 



