44 SUPPLEMENT i 



zoophyta was replaced by that of mollusca, for the second, 

 while it replaced that of litJiophyta, for the fourth, which was 

 suppressed. 



In the eleventh edition, the class of worms is divided into 

 five orders : Intestina, Mollusca, Testacea, lAtliopliyta, and 

 Zoophyta, and the genera which at present constitute the class 

 of red-blooded worms, were parcelled out, some as lumhricus 

 and liirudo in the first order ; others as ierebella, aphrodita 

 and nereis in the second ; and finally, some as serpula and 

 sahella in the fourth, in consequence of the tube in which they 

 live. 



In the interval fi'om this edition of the Systema Natures, 

 to the last, which appeared in 1766, and which was very 

 closely followed by Gmelin's, the thirteenth, some very im- 

 portant researches on the animals of the Linnsean class of 

 woiTus, and especially on the chetopoda, or setigerous anne- 

 lida, were given to the world. The labours of Pallas, in 1766, 

 on the aphrodit(B, the nereides, and the serpulcB, were the 

 true origin of every thing judicious, which has been subse- 

 quently proposed concerning this class of animals. He 

 made the very important observation, which he had already 

 applied to the mollusca proper, that the presence or absence 

 of a calcareous envelope did not constitute a sufficient ground 

 for placing in two separate orders, animals which, in other re- 

 spects, are similarly organized. Thus he approximated together 

 the aphrodita^ and the nereides of the order mollusca of Lin- 

 naeus, and the serpula; and amphitrita; of that of his testacea, 

 saying, that they should form a distinct order, constituting the 

 passage to the Zoophytes, and to which, he adds, may be 

 joined the lumbrici, the hirudines, the ascarides, gordius, and 

 the taeniae or tape-worms ; all which has been done since, has 

 been founded on this observation of Pallas. 



To two Danish naturalists, Otho Frederic MuUer, and Otho 



