74 SUPPLEMENT , 



reach of the species uihabiting tubes, or which they go in 

 search of when they can move^ as do the aphrodites, the ara- 

 phinomae, the nereides, &c. The species which have the 

 mouth armed with corneous or calcareous teeth, whether 

 trenchant or molar, must use as food living animals, and 

 often such as are of a considerable size. Nereides have 

 even been found in the holes of teredines, from which it has 

 been concluded, that the former preyed upon them. The 

 larger nereides with many teeth may doubtless attack pretty 

 large animals, even fish perhaps not excepted. 



There are chetopoda, on the other hand, which appear to 

 feed only on organic molecules, or at least on the portions of 

 organized bodies contained in the soil which they inhabit: 

 such are the arenicolas and lumbrici, whose intestinal canal is 

 constantly found filled with earth and sand. It is true that 

 their mouth is but a simple orifice, without any buccal appa- 

 ratus. 



The means which the animals of this class employ to pro- 

 cure their food cannot certainly be very inventive ; for those 

 which live in tubes, it is sufiicient to agitate in all directions 

 the barbies with which their heads are adorned, to draw to- 

 wards their mouth a cuiTent of water, which must bring with 

 it a certain number of little animals, or even to seek them and 

 draw them towards the mouth by a sort of prehension, executed 

 with the assistance of their branchial cirri, or of the barbies, 

 when they are provided with them. Certain of those tubico- 

 iar species may thus remain in ambush at the entrance of their 

 tube, and so much the more easily, as it is often composed of 

 grains of sand, or of particles of shells, in all respects similar 

 to those which constitute the smrounding soil. 



The free and vagrant species may go in search of the 

 objects which suit them, but in all probability they lay no 

 ambush. 



The lumbrici, thalassema), and the arenicola), have only to 



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