ON THE BRITISH ANNELIDA. 161 



appeared from the pen of Gesner, presenting a synoptic view of the state of 

 knowledge with reference to this class of animals. The alphabetical order 

 observed by Gesner in the arrangement of the Vermes, was violated by AI- 

 drovandus. It is remarked by Cuvier as singular, that to Aldrovandus and 

 his disciples the Chaetopodaof Gesner, and the setigerous Annelida of recent 

 observers, should have been unknown ; and no less is it to be wondered at, 

 that this writer and his abridgers were unacquainted with the deep differences 

 of zoological characters which separate the slug from the earth-worm — a di- 

 stinction, too, which Isidore of Seville had already precisely defined — (" Fer- 

 mis Umax dictus eo quod in limo nascitur, tmde et sordidiis semper et immun- 

 dus habetur"'). The Chsetopoda, or setiferous worms, are however mentioned 

 in the seventh book of Aldrovandus, in allusion to aquatic insects. The 

 Nereids are comprised under the appellation of Sea-Scolopendr^. The Gor- 

 dius is called ^^ seta vel vitalis aquaticus," and which has been denominated 

 Gordius from the habit of twisting itself up like the Gordian knot. The 

 Ololygon of Theon appears to have been the same worm. By this author 

 the Sipunculi of Rondelet are spoken of as sea-leeches ; under the same name 

 are characterized the Arenicola of Belon. The epoch of Ray had now ar- 

 rived, distinguished as it was by a radical regeneration of natural science. 

 In the group Insecta of Ray were comprehended all articulate animals : 

 amongst other subdivisions of this class, that of the Apoda, including those 

 worms which live in the earth, and that of Infesfince, those which infest the 

 bodies of animals, may be recognised. Under the head Insecta terrestria, Ray 

 ranks (the Myriapods) the true Scolopendras ; and in his aquatic division of 

 Insecta, the Sea-Scolopendrae or Nereids occur. In the first edition of his 

 * Systema Naturae,' Linnaeus extended the term Vermis to all animals except 

 the Vertebrata and Insecta ; excluding however the insect-worms of Ray from 

 his class Vermis. After this first essay appeared an account of the genera 

 Amphitrite, Nereis and Aphrodita, which belong to the Chaetopoda. In the 

 subsequent edition of IJnnasus, the name Intestines was substituted for Rep- 

 tilfa for the first order. In a following edition the class of Worms is sub- 

 divided into five orders — Intestina, Mollusca, Testacea, Lithophyta, and 

 Zoophyta, and the genera which at present constitute the class of red-blooded 

 worms were parcelled out, some as Lumbricus and Hirudo in the first order ; 

 others, as Terebella, Aphrodita. and Nereis, in the second ; and finally, some, as 

 Serpula and Sabella, in the fourth, in consequence of the tube in which they 

 live. The true zoological limits of the Annelida were, however, only con- 

 fusedly determined by the observers of nature antecedently to the time of 

 Pallas (1766). To the sagacity and industry of this naturalist, science is 

 indebted for the first clear definition of the boundaries of this class. By his 

 successful researches on the Aphroditce, the Nereides and the Serpula, a 

 material advance was imparted to the knowledge of the Annelida as a class. 

 He recognised the principle, that the presence or absence of a calcareous en- 

 velope did not constitute a sufficient ground for placing in two separate 

 orders animals which in other respects are similarly organized. The Aphro- 

 dites and Nereids of the order Mollusca of Linnaeus, and the Serpulce and 

 Amphitritce of his order Testacea, were accordingly grouped into a single 

 order, through which lay the passage to the Zoophytes. To this order were 

 also annexed the Hirudines, Lumbrici, the Ascarides, the Gordius, and the 

 T(Bni(B. The data thus accumulated by Pallas constitute the foundation of the 

 modern classification of the Worm-tribe. 



After this the Nereids were made the subject of extensive inquiries by the 

 two Danish philosophers, O. T. Miiller and O. Fabricius. By these authors 

 additions were also made to the history of the Ndides and Amphitrites. 



1851. i^ 



