52 SUPPLEMENT , 



diately to follow the Crustacea, and conduct to the insects ; 

 but, in consequence of their form, of the trifling development 

 of their organs of locomotion, and especially in consequence 

 of the mode of respiration in insects, which appears to hold 

 the place of the circulation of the blood, he thinks that the 

 worms ought to be placed between the insects and the zoo-? 

 phytes ; that is, between the class myriapoda, with which 

 he finishes the former, and that of Helminthii, or intestinal 

 worms, wdth which he commences the latter. 



M. de Blainville intended to place this class between the 

 myriapoda and the apoda, or intestinal worms. Thus we 

 should pass, almost insensibly, to the sub-annelida, and by 

 them to the holothurise, which would properly commence the 

 zoophytes. But it was necessary to place between those two 

 types the mollusca, which, after the vertebrated animals, also 

 form a parallel line, proceeding to, and arriving at the zoo- 

 phytes, through the ascidiae. 



Respecting the animals of which we are now writing, there 

 is but little of any thing important in the study of them, ex- 

 cept what may be derived from it by natural philosophy. 

 Their utility to the human species is but slight indeed. The 

 larger nereides and the arenicolse are, however, much used as 

 baits for catching fish, especially whiting and mackerel. They 

 even constitute a small object of commerce with the inhabit- 

 ants of the coasts of the Atlantic and the Mediterranean. The 

 lumbrici, or earth-worms, are also employed to catch fresh- 

 water fish, and among others, eels, and fish in general, that 

 live in mud. 



We must, how^ever, now take a brief view of the organiza- 

 tion of the chetopoda. 



The organization of these animals has been studied in its 

 external parts by Pallas, by Muller, and very particularly by 

 Otho Fabricius, and M. Savigny. As to their internal organi- 



